DHS ANALYTICAL 

STUDIES 37

The Effects of Fertility Behavior on Child 

Survival and Child Nutritional Status: 

Evidence from the Demographic and

Health Surveys, 2006 to 2012

FEBRUARY 2014

This publication was produced for review by the United States Agency for International Development. It was prepared by 

Shea Rutstein and Rebecca Winter of ICF International.

DHS Analytical Studies No. 37 

The Effects of Fertility Behavior on Child Survival and 

Child Nutritional Status: Evidence from the Demographic 

and Health Surveys, 2006 to 2012 

Shea Rutstein 

Rebecca Winter 

ICF International 

Rockville, Maryland, USA 

February 2014 

Corresponding author: Shea Rutstein, International Health and Development, ICF International, 530 

Gaither Road, Suite 500, Rockville, MD 20850, USA; telephone: +1 301–572–0950; fax: +1 301–572–

0999; email: Shea.Rutstein@icfi.com 
Acknowledgment: The authors thank Jessica Yi for help with the literature review and Iqbal Shah for 

serving as the external reviewer. 

Editors: Richard Mason and Nancy Klein 

Document Production: Yuan Cheng 

This study was carried out with support provided by the United States Agency for International 

Development (USAID) through The DHS Program (#GPO–C–00–08–00008–00). The views expressed 

are those of the authors and do not necessarily reflect the views of USAID or the United States 

Government. 

Recommended citation: 

Rutstein, Shea, and Rebecca Winter. 2014. The Effects of Fertility Behavior on Child Survival and Child 

Nutritional Status: Evidence from the Demographic and Health Surveys, 2006 to 2012. DHS Analytical 

Studies No. 37. Rockville, Maryland, USA: ICF International. 
iii 

Contents 

List of Tables ............................................................................................................................................... v 

List of Figures ............................................................................................................................................. vi 

Preface ........................................................................................................................................................ vii 

Executive Summary ................................................................................................................................... ix 

Glossary of Terms ....................................................................................................................................... x 

Introduction and Rationale ........................................................................................................................ 1 

Literature Review .................................................................................................................................. 1 

Methods and Data ....................................................................................................................................... 7 

Methods ................................................................................................................................................. 7 

DHS Data Used in the Study ............................................................................................................... 11 

Creation of the Pooled Data Set ......................................................................................................... 13 

Results ........................................................................................................................................................ 15 

Univariate Results .............................................................................................................................. 15 

Bivariate Results ................................................................................................................................. 27 

Multivariate Results ............................................................................................................................ 37 

Discussion .................................................................................................................................................. 53 

References .................................................................................................................................................. 59 

Appendix .................................................................................................................................................... 63 

v 

List of Tables 

Table 1. List of surveys, by year ............................................................................................................... 13 

Table 2. Distribution of births 0 to 179 months prior to survey by duration of preceding birth–to–

conception interval, 45 DHS surveys, 2006–2012 ..................................................................... 17 

Table 3. Distribution of births 0 to 179 months prior to survey by the mother’s age at child’s birth, 

45 DHS surveys, 2006–2012 ...................................................................................................... 19 

Table 4. Distribution of births 0 to 179 months prior to survey by the child’s birth order, 45 DHS 

surveys, 2006–2012 .................................................................................................................... 21 

Table 5. Distribution of births 0 to 179 months prior to survey by maternal fertility–related risk 

factors, 45 DHS surveys, 2006–2012 ......................................................................................... 23

Table 6. Distribution of births 0 to 179 months prior to survey by maternal fertility–related risk 

factors, 45 DHS surveys, 2006–2012 ......................................................................................... 26

Table 7. Unadjusted relative risk of mortality by duration of preceding birth–to–conception 

interval, mother’s age at child’s birth, and the birth order, children born 0 to 179 months 

prior to the survey, 45 DHS surveys, 2006–2012 ....................................................................... 29 

Table 8. Unadjusted relative risk of mortality by the mother’s fertility–related risk, children born 0 

to 179 months prior to the survey, 45 DHS surveys, 2006–2012 ............................................... 31 

Table 9. Unadjusted relative risk of mortality by the mother’s fertility-related risk, children born 0 

to 179 months prior to the survey, 45 DHS surveys, 2006–2012 ............................................... 32 

Table 10. Unadjusted odds ratios for stunting, underweight, and wasting by duration of preceding 

birth–to–conception interval, mother’s age at child’s birth, and birth order, living children 

age 0 to 59 months at survey, 42 DHS surveys, 2006–2012 ...................................................... 33 

Table 11. Unadjusted odds ratios for stunting, underweight, and wasting by the mother’s fertility–

related risk, living children age 0 to 59 months at survey, 45 DHS surveys, 2006–2012 .......... 35 

Table 12. Unadjusted odds ratios for stunting, underweight, and wasting by the mother’s fertility–

related risk, living children age 0 to 59 months at survey, 45 DHS surveys, 2006–2012 .......... 36 

Table 13. Adjusted relative risk of mortality by duration of preceding birth–to–conception interval, 

mother’s age at child’s birth, and the birth order, children born 0 to 179 months prior to 

the survey, 45 DHS surveys, 2006–2012 .................................................................................... 38 

Table 14. Adjusted relative risk of mortality by the mother’s fertility–related risk, children born 0 to 

179 months prior to the survey, 45 DHS surveys, 2006–2012 ................................................... 45 

Table 15. Adjusted relative risk of mortality by the mother’s fertility–related risk, children born 0 to 

179 months prior to the survey, 45 DHS surveys, 2006–2012 ................................................... 47 

Table 16. Adjusted odds ratios for stunting, underweight, and wasting by duration of preceding 

birth–to–conception interval, mother’s age at child’s birth, and birth order, living children 

age 0 to 59 months at survey, 45 DHS surveys, 2006–2012 ...................................................... 48 
vi 

Table 17. Adjusted odds ratios for stunting, underweight, and wasting, by the mother’s fertility–

related risk, living children age 0 to 59 months at survey, 45 DHS surveys, 2006–2012 .......... 50 

Table 18. Adjusted odds ratios for stunting, underweight, and wasting by the mother’s fertility–

related risk, living children age 0 to 59 months at survey, 45 DHS surveys, 2006–2012 .......... 52 

Table 19. Calculation of population–attributable risks for infant and under–five mortality by duration 

of preceding birth–to–conception interval, mother’s age at child’s birth, and the birth 

order, 45 DHS surveys, 2006–2012 ............................................................................................ 55 

Appendix Table A1. Distribution of births 0 to 179 months and 0 to 59 months prior to survey by 

control variables used in multivariate analyses, 45 DHS surveys, 2006-2012 ........................... 63 

List of Figures 

Figure 1. Adjusted relative risks of under–five and child (one to four years) mortality by length of 

birth–to–conception interval, 45 DHS surveys between 2006 and 2012 .................................... 39 

Figure 2. Adjusted relative risks of infant and post–neonatal mortality by length of birth–to–

conception interval, 45 DHS surveys between 2006 and 2012 .................................................. 40 

Figure 3. Adjusted relative risks of neonatal and early neonatal mortality by length of birth–to–

conception interval, 45 DHS surveys between 2006 and 2012 .................................................. 41 

Figure 4. Adjusted relative risks of neonatal and under–five mortality by mother’s age at birth, 45 

DHS surveys between 2006 and 2012 ........................................................................................ 42 

Figure 5. Adjusted relative risks of under–five mortality by birth order, 45, DHS surveys between 

2006 and 2012 ............................................................................................................................ 43 

Figure 6. Adjusted relative risk of under–five mortality by combinations of extra–risk fertility 

behavior ...................................................................................................................................... 46 

Figure 7. Adjusted relative odds of stunting and underweight by birth–to–conception interval, 42 

DHS surveys between 2006 and 2012 ........................................................................................ 49 

Figure 8. Adjusted relative odds of stunting by combinations of fertility behavior risk factors, 42 

DHS surveys between 2006 and 2012 ........................................................................................ 52 

Figure 9. Adjusted relative risk of being alive and not stunted at five years of age, by duration of 

preceding birth–to–conception interval ...................................................................................... 56 

Figure 10. Adjusted relative risk of being alive and not stunted at five years of age, by mother’s age 

at child’s birth ............................................................................................................................. 57 

Figure 11. Adjusted relative risk of being alive and not stunted at five years of age, by child’s birth 

order ............................................................................................................................................ 58 
vii 

Preface 

One of the most significant contributions of The DHS Program is the creation of an internationally 

comparable body of data on the demographic and health characteristics of populations in developing 

countries. 

The DHS Comparative Reports series examines these data across countries in a comparative framework. 

The DHS Analytical Studies series focuses on analysis of specific topics. The principal objectives of both 

series are to provide information for policy formulation at the international level and to examine 

individual country results in an international context. 

While Comparative Reports are primarily descriptive, Analytical Studies provide in–depth, focused 

studies on a variety of substantive topics. The studies are based on a varying number of data sets, 

depending on the topic being examined. These studies employ a range of methodologies, including 

multivariate statistical techniques. 

The staff of The DHS Program, in conjunction with the U.S. Agency for International Development 

(USAID), selects the topics covered in Analytical Studies. 

It is anticipated that the DHS Analytical Studies will enhance the understanding of analysts and 

policymakers regarding significant issues in the fields of international population and health. 

Sunita Kishor 

Director, The DHS Program

ix 

Executive Summary 

The current study is the latest in a series of three based on DHS surveys that examine the relationship 

between spacing between births or pregnancies and infant and child mortality and nutritional status. The 

first study used data from 17 DHS surveys between 1990 and 1997. The second study used data from 52 

different DHS surveys from 2000 to 2005. The present study includes data from 45 DHS surveys between 

2006 and 2012 and extends the analysis by reporting on mother’s age at birth and child’s birth order in 

addition to the preceding birth–to–conception interval reported in the previous two studies. 

More than 1.1 million births that occurred in the 15 years prior to the surveys are included in the analyses 

of mortality under age five years and at ages one to five years. More than 420,000 births in the five years 

preceding the surveys are included for the analyses of mortality in infancy. Nutritional status is analyzed 

for more than 340,000 living children under age five years. The analysis methodology includes bivariate 

and multivariate Cox hazard regression for mortality and multivariate logistic regression for nutritional 

status. 

The results for spacing are quite similar to those found in the preceding studies, confirming the 

importance of waiting a period of time to conceive again after a birth. While birth–to–conception intervals 

of fewer than 18 months (i.e., a birth–to–birth interval of 27 months) incur an increased risk of neonatal 

mortality, intervals of fewer than 36 months birth to conception incur an increased risk of mortality at 

ages one to four years. Risks of mortality increase during infancy for birth–to–conception intervals longer 

than 60 months. Population–attributable risk calculations indicate 26 percent excess under–five mortality 

due to birth–to–conception intervals shorter than 36 months. The analysis of nutritional status indicates 

that the longer the preceding birth–to–conception interval, the less likely a child is to be stunted 

(chronically malnourished) and underweight for his or her age. However, the likelihood of wasting, being 

a measure of acute malnutrition, is not affected. 

Mother’s young age at birth (less than 18 years) increases the risk of dying for children at all ages under 

five years, and a mother’s being 35 years or older increases the child’s risk of dying during infancy. After 

infancy, however, the chances of dying for children of older mothers are slightly lower than the chances 

for children whose mothers were 18–24 years when the child was born. Children of older mothers are also 

less likely to be stunted and underweight. Being born to a mother under age 18 years increases a child’s 

likelihood of being stunted and underweight. 

First–born children have a substantially higher risk of mortality at all ages under age five years, even 

when a young mother’s age at birth is taken into account. Higher birth order does not affect neonatal 

mortality but increases post–neonatal, ages one to four, and all under–five mortality, and slightly 

increases rates of stunting but not underweight or wasting. 

The study indicates that the more fertility behavioral risk factors a child faces, the greater are the chances 

of dying and being malnourished. A child with three risk factors is twice as likely to die before reaching 

age five as a child with no risk factors, and if the child survives, she or he is 30 percent more likely to be 

suffering from chronic malnutrition. 
x 

Glossary of Terms 

Acute undernutrition (wasted): Defined as a child whose weight for height is below –2 standard 

deviations from the median of the National Center for Health Statistics, Centers for Disease Control and 

Prevention (NCHS/CDC) reference for weight for height. 

Birth order: A count of all live births the mother had before the index child.

Child mortality: Refers to deaths to children at ages one to four years among children who survive to age 

one year. 

Chronic undernutrition (stunted): Defined as a child whose height for age is below –2 standard 

deviations from the median of the NCHS/CDC reference for height for age.

Early neonatal mortality (ENN): Refers to deaths that occur 0 to 6 days after live birth.

Neonatal mortality (NN): Refers to deaths within the first 30 days among all children born alive.

Infant mortality: Refers to deaths to children at ages 0–11 months among all children born alive.

Odds ratio (OR): Defined as the ratio of the odds of an event occurring in one group relative to the odds 

of it occurring in another group.

Overall undernutrition (underweight): Defined as a child whose weight for age is below –2 standard 

deviations from the median of the NCHS/CDC reference for weight for age.

Population–attributable risk (PAR): Defined as the proportion of cases (e.g., deaths) that would not 

occur if a given risk factor were eliminated. The attributable risk in a population depends on the 

prevalence of this risk factor and the strength of its association (relative risk) with the outcome. 

Post–neonatal mortality (PNN): Refers to deaths at 1–11 months after live birth. 

Preceding birth–to–conception interval: Refers to the number of months between the date of the 

conception of the child under study (index child) and the date of the immediately preceding birth to the 

mother, if any. 

Preceding birth–to–birth interval: Refers to the number of months between the date of birth of the child 

under study (index child) and the date of the immediately preceding birth to the mother, if any.

Risk ratio (RR): A measure of the risk of a certain event (i.e., infant mortality) happening in one group 

compared with the risk of the same event happening in another group. 

Singleton birth: A birth that is not a twin or other multiple birth.

Under–five mortality: Refers to deaths to children less than five years of age among all children born 

alive.
1 

Introduction and Rationale 

This study examines three fertility–related behavioral factors that are known to affect child survival 

and health, namely, the length of the preceding birth–to–conception interval, maternal age at the 

child’s birth, and the child’s birth order. Numerous studies have examined the effects of these three 

maternal characteristics on child survival and health outcomes. However, the challenge has been 

disentangling the separate effects of each of these characteristics, because they are closely related to 

one another. This study takes advantage of data from all recent DHS surveys between 2006 and 

2012 and examines the effects of each characteristic on child survival and nutritional status while 

holding the other two constant and controlling for an extensive set of potential confounding 

variables. This study is intended to contribute to understanding the relative importance of each 

characteristic and to inform child survival and nutrition policies. 

Literature Review 

Preceding birth–to–conception interval 

The harmful effects of a short or long preceding birth–to–conception interval1

 for maternal and child 

health have been studied extensively, with consistent findings dating back to as early as the 1920s. 

Various causal mechanisms could explain the effect of the length of the preceding birth interval on the 

risk of child mortality. In a review of 58 observational studies, Conde–Agudelo and colleagues identified 

several plausible causal mechanisms, including folic acid deficiency, cervical insufficiency, vertical 

transmission of infections, inadequate breastfeeding, and sibling competition (Conde–Agudelo, Rosas–

Bermúdez, and Kafury–Goeta 2006). For an in–depth discussion of the literature on this relationship, see 

previous studies by Rutstein (Rutstein 2005; Rutstein 2008). 

In brief, the effect of short intervals has been shown repeatedly to be one of the most important factors 

affecting the mortality of infants and young children under age five years. Early studies identified a U–

shaped pattern between the length of the preceding birth–to–conception interval and infant mortality 

(Hughes, Hunter, and Woodbury 1923; Woodbury 1925). Subsequent studies demonstrated that even after 

adjusting for a variety of confounding factors, the effect of birth interval on young child mortality persists 

(Alam 1995; Alam and David 1998; Bhalotra and van Soest 2006; Conde–Agudelo, Rosas–Bermúdez, 

and Kafury–Goeta 2006; DaVanzo et al. 2008; Hosseinpoor et al. 2006; Koenig et al. 1990; Miller et al. 

1992; Mozumder et al. 1998; Zenger 1993). Studies have found that the harmful effects of a non–optimal 

preceding birth interval are concentrated in early infancy (Koenig et al. 1990), suggesting that prenatal 

conditions, rather than household factors like sibling competition, are likely to explain the effect of birth 

interval (Boerma and Bicego 1992). However, studies have also found that the effect of a short–preceding 

birth interval on child mortality are stronger if the preceding child is still alive, suggesting that sibling 

completion does play a role (DaVanzo et al. 2008). In recent years, multi–country studies have sought to 

identify the optimal birth interval for child survival. Rutstein (2005 and 2008) found that for neonatal 

mortality and infant mortality the risk of dying was lowest for children with a preceding birth–to–birth 

interval of 36–47 months, while for child mortality risk continued to decrease with increasing length of 

the preceding birth interval. 

 

1

 While this study uses birth to next conception of live birth intervals, many studies have used birth-to-birth 

intervals, the difference being the length of gestation, taken as nine months where data for gestation length do not 

exist. 
2 

In addition to the effects of birth interval on child survival, studies have documented a strong relationship 

between the length of the preceding birth interval and chronic and general undernutrition such that 

nutrition outcomes are poorer for children with shorter preceding birth intervals (Dewey and Cohen 2007; 

Rutstein 2005). In a systematic literature review of the effects of birth spacing on maternal and child 

nutritional status, Dewey and Cohen (2007) found that among 22 studies on this topic identified since 

1966, the longer the birth interval, the lower the risk of malnutrition in some but not all populations. In 

countries with significant results, a previous birth–to–birth interval of at least 36 months was associated 

with a 10 to 50 percent reduction in stunting. 

Maternal age 

The effects of maternal age on infant and early child survival and health have been studied extensively, 

but with mixed findings. Children born to very young women and to older women have often been 

observed to have higher levels of mortality. However, some authors provide evidence that this association 

can be explained away by young women’s social disadvantage and other confounding factors (Geronimus 

1987; Reichman and Pagnini 1997). Others provide evidence that the observed maternal–age effect 

persists after adjusting for social factors (Finlay, Özaltin, and Canning 2011; Fraser, Brockert, and Ward 

1995; Kumar et al. 2013), suggesting a biological effect. Several plausible biological explanations could 

explain the excess mortality observed among young mothers. Young teenage mothers have often not yet 

reached full physiological and reproductive maturity, thereby increasing their risk of complications during 

pregnancy and birth as well as the likelihood of inadequate weight gain during pregnancy. Young mothers 

who are still growing themselves also may compete for nutrients with the fetus (Fraser, Brockert, and 

Ward. 1995). Young teenage mothers’ psychological immaturity also could impact the child’s care. 

However, the observed association also could be explained by social factors or by collinearity between 

maternal age and birth order. 

Much of the literature exploring the effect of young maternal age on birth outcomes has relied on United 

States–based data (Fraser, Brockert, and Ward 1995; Geronimus 1987; Reichman and Pagnini 1997). 

Within the context of the United States, teenage pregnancy is associated with social and economic 

disadvantage, and teenage mothers have been shown to use prenatal care and health services at a lower 

rate (Reichman and Pagnini 1997). Some studies have found that after controlling for socioeconomic 

circumstances and health status and care–seeking–such as the mother’s education, insurance status, 

marital status, use of prenatal care, reproductive history, smoking and alcohol use, and the mother’s 

health status–young age itself was no longer associated with additional risk (Reichman and Pagnini 

1997). 

Several studies in less developed countries have also found that adjusting for sociodemographic factors 

eliminates the bivariate U–shaped association between maternal age and early child mortality (Akinyemi, 

Bamgboye, and Ayeni 2013). Akinyemi and colleagues (2013), for example, found no evidence of an 

association between maternal age (< 18, 18–34, 35+ years) and under–five mortality in Nigeria, in a 

hazard model that adjusted for a range of socioeconomic, behavioral and health, environmental, and 

biodemographic factors. Handa and colleagues found that the risk of under–five mortality was lower for 

women who had their first birth at 16 years of age or older compared with women who gave birth at a 

younger age in only one of four countries in Southern Africa (Mozambique but not in Malawi, Tanzania, 

or Zambia), in an adjusted Cox regression model (Handa, Koch, and Ng 2010). 

However, other studies in less developed countries have found an independent, persistent association 

between maternal age and early child mortality, suggesting underlying physiological causal pathways 

(Finlay, Özaltin, and Canning 2011; Ikamari 2013; Kumar et al. 2013; van der Klaauw and Wang 2011). 

Van der Klaauw and Wang (2011) found that the expected U–shaped relationship between maternal age 

and neonatal, post–neonatal, and child (years one to four) mortality persisted after adjusting for an array 
3 

of sociodemographic characteristics among children in rural India, including state, sex of child, preceding 

birth interval, first –birth order, ethnicity, mother’s marital status, education, wealth decile, and various 

household and village characteristics. For example, the risk of neonatal mortality was lower among 

mothers who were 20–25 and 26–31 than for women under age 20, and was highest for women of at least 

32 years. Ikamari (2013) also found that neonatal and post–neonatal mortality varied significantly 

according to maternal age at birth, in adjusted Cox regression models. However, rather than follow the U–

shaped risk pattern, the risk of both neonatal and post–neonatal mortality increased incrementally with 

age, such that the risk was lowest in the < 20 age group, higher in the 20–34 group, and highest in the 35+ 

group. Similarly, Kumar and colleagues (2013) found that the adjusted probability of early neonatal death 

was highest among women under age 20 at the child’s birth and lowest among women at least 25 years 

old at the child’s birth. 

Some studies have focused specifically on the association between the mother’s older age and birth 

outcomes (Lisonkova et al. 2010). In a study of a representative sample of women with singleton births in 

British Columbia, Lisonkova and colleagues (2010) examined whether older maternal age was associated 

with three outcomes–stillbirth, neonatal death, and preterm birth. They found that older age (being 35–39, 

and 40 or older) was associated with the risk of stillbirth and preterm birth after adjusting for parity, 

marital status, neighborhood income, rural residence, smoking, alcohol and drug use during pregnancy, 

prenatal care, infant’s sex, ethnicity, previous induced abortion, and previous spontaneous abortion. The 

association between maternal age and neonatal mortality was not significant in the adjusted model. They 

also found that parity significantly modified the associations between maternal age and preterm birth and 

between maternal age and being small for gestational age, such that the effect was stronger among 

primiparous women. 

Several of the aforementioned studies that have found a positive, independent effect of maternal age on 

child survival have been limited to women’s first birth in order to better isolate the effect of maternal age 

from the effect of birth order (Finlay, Özaltin, and Canning 2011; Fraser, Brockert, and Ward 1995). For 

example, in a sample of singleton first births to women in the United States, Fraser (1995) found that 

children born to mothers between the ages of 13 and 17 years had a higher risk of being born with a low 

birth weight, being delivered prematurely, or being small for gestational age than children whose mothers 

were between the ages of 20–24 years at the time of their birth, after adjusting for educational attainment, 

marital status, and prenatal care. The risk of these three outcomes was also elevated among mothers age 

18–19 compared with women age 20–24. More recently, Finlay and colleagues (2011) conducted a multi–

country analysis of DHS data from 55 countries to investigate the association between maternal age and 

infant mortality, child nutritional status, diarrhea, and anemia. They found that even after controlling for a 

range of socioeconomic factors, the U–shaped association between maternal age and infant mortality 

persisted, with optimal outcomes to women in the 27–29 year range. 

Although studies limited to first births are informative in helping to isolate the effect of age versus the 

effect of birth order, they are not generalizable to all births, because the effect of a woman’s age at first 

birth could differ from the effect of her age at later births. The current study will include all births as well 

as measures of all three fertility–related characteristics–maternal age, preceding birth interval, and birth 

order–in order to provide additional evidence on the independent effects of each. 

Studies have also found maternal age to be significantly associated with measures of child health and 

nutrition (Finlay, Özaltin, and Canning 2011; Vitolo et al. 2008). Using cross–sectional data on children 

age one month to five years in southern Brazil, Vitolo and colleagues (2008) found that young maternal 

age is associated with being born with a low birth weight and with wasting. Using DHS data from 55 

countries, Finlay and colleagues (2011) found that among women’s first births, maternal age was 

associated with children’s being underweight, stunted, and having had diarrhea. The relationship with 
4 

these outcomes was linear, such that the risk of each outcome decreased with increasing age, after 

adjusting for sociodemographic factors. 

Birth order 

The association between birth order and child mortality is often described as U–shaped, with higher 

mortality levels among first births and high–order births. However, studies exploring determinants of 

child mortality have not consistently found birth order to retain significance in adjusted models (Saha and 

van Soest 2013). 

Some studies have found a significant association between birth order and child mortality, even after 

controlling for potential confounders (Handa, Koch, and Ng 2010). Handa and colleagues (2010) 

examined trends in determinants of under–five and under–two mortality over time in four countries in 

Southern Africa. In their full Cox regression models, they included a measure of the mother’s parity (total 

number of live births, measured continuously) as well as a categorical measure of the child’s birth order 

(first, second, and third or higher). They interpret parity as a measure of maternal depletion and 

categorical birth order as a measure of the child’s lived experience in the home. In the adjusted model, 

they found that the mother’s parity was positively associated with the risk of under–five and under–two 

mortality in Malawi, Mozambique, Tanzania, and Zambia, indicating the expected effect of maternal 

depletion. Higher birth order, on the other hand, was negatively associated with the risk of under–five and 

under–two mortality, such that in all four countries, children of third or higher birth order had a roughly 

30 percent lower risk of dying by age five than first and second births. Uddin and colleagues (2009) found 

that the child mortality rate increased steadily with increasing birth order. They concluded that this 

finding reflects a “more intense competition faced by higher birth order children in terms of care givers 

time, medical resources, and nutritious food” (Uddin, Hossain, and Ullah 2009). 

Other studies have not found birth order to be an important determinant of child survival (Saha and van 

Soest 2013). Saha and van Soest (2013) did not find a significant association between birth order and 

infant mortality, after adjusting for a range of factors, among births in the Matlab area of Bangladesh. In 

this study, birth order was included as a continuous variable with a quadratic term. They did, however, 

find that birth order was significantly associated with birth interval (another outcome that was examined 

in the study), such that higher order births tend to have shorter preceding intervals. 

As mentioned earlier, separating the effects of maternal age from the effects of the child’s birth order is 

challenging. Depending on the study design, it is not always possible to determine how much excess risk 

can be attributed to first birth order beyond the risk of young maternal age, or to high birth order, beyond 

the risk of older maternal age. Rather than attempt to measure separate effects, Rossiter and colleagues 

(1985) examined the combined effects of these factors, finding that among singleton births, perinatal 

survival is poorest among first births to mothers age 15 or younger and to high–order births to women age 

30 or older (Rossiter et al. 1985). 

Some useful studies have investigated the interaction between birth order and maternal age. In a study 

using data from a Demographic Surveillance System site in Matlab, Bangladesh, Alam (2000) found that 

among teenage mothers, the risk of neonatal mortality was higher for their second birth than for their first 

birth in an adjusted logistic regression model. Among women age 20–24, the risk of neonatal and post–

neonatal mortality was higher for first births than for second births. Alam interprets this finding as 

evidence of a depletion effect among young teenage mothers with multiple births. 

Children’s nutritional status has been found to depend on the child’s birth order, perhaps more 

consistently than their survival. The number of siblings a child has increases his or her odds of poor 

nutritional outcomes, possibly through sibling competition, the mother’s availability for child care, or the 
5 

correlation between large family size and lower socioeconomic status (Magvanjav et al. 2013; Vitolo et 

al. 2008). In a study using a cross–sectional sample of children in Sao Leopoldo, Brazil, Vitolo (2008) 

found the number of siblings to be positively associated with children’s odds of being stunted, after 

controlling for socio–demographic factors. Similarly, a recent study of children in Bolivia found that the 

presence of each additional older brother or younger sister was negatively associated with arm measures 

in girls (Magvanjav et al. 2013). 

7 

Methods and Data

Methods 

The methodology used in this study is the pooled data analysis of retrospective survey data of The DHS 

Program using both bivariate and multivariate techniques. The pooling of the data sets permits better 

estimation of effects due to the large size of the data set and, hence, better control of random sampling 

variation. 

Dependent variables 

The study examines nine outcomes: six young childhood mortality outcomes (early neonatal, neonatal, 

post–neonatal, infant, child, and under–five mortality) and three nutrition–related outcomes (stunting, 

wasting, and underweight). For early neonatal, neonatal, post–neonatal, and infant mortality, the 

dependent variables are life–table probabilities of mortality based on survival status and age at death for 

children who were born in the five years prior to each survey. For child and under–five mortality, the 

dependent variables are life–table probabilities of mortality based on survival status and age at death for 

children who were born in the 15 years prior to each survey.2

 Analyses of mortality at the youngest ages 

are restricted to the five years prior to each survey in order to take advantage of information on maternal 

and birth–related care that is only available for these births. Because birth care is a less important 

determinant of older child mortality, this restriction was not necessary. 

For nutritional status, the dependent variable is the percentage of young children who are stunted, wasted, 

or underweight among living children under age five years. As part of the interviewing procedure, the 

DHS surveys routinely collect the height and weight of children under age five years. Together with the 

child’s age, this information can be used to assess the nutritional status of children when compared to a 

reference standard using standard deviation values (z–scores). The DHS data are compared to the 

NCHS/CDC international reference standards for height for age, weight for age, and weight for height. 

Children whose z–scores are below minus two standard deviations from the median (–2 sd) on the 

reference standard are considered moderately or severely undernourished. Chronic undernutrition, or 

stunting, is determined by a height–for–age z–score below 2 standard deviations below the median. Acute 

undernutrition, or wasting, is measured by a z–score less than –2 sd for weight for height; overall 

undernutrition, or underweight, is measured by a z–score less than –2 sd for weight for age. 

The dependent variables are summarized below: 

• ENN–Early neonatal mortality, death at 0–6 days after birth 

• NN–Neonatal mortality, death at 0–30 days and <1 month after birth 

• PNN–Post–neonatal mortality, death at 1–11 months after birth 

• IMR–Infant mortality, death at 0–11 months after birth 

• Child mortality, death at 12–59 months after birth 

• Under–five mortality, death at 0–59 months after birth 

• Chronic undernutrition (stunted), <–2 sd on NCHS/CDC reference for height for age 

 

2

 Because the age range of interviewed women is 15-49 years at the time of the survey, data on births occurring 

earlier than 15 years prior to the survey are limited to mothers ages 15-34 years. To avoid substantial bias due to this 

age restriction, the 15-year window is used in the analyses here. 
8 

• Acute undernutrition (wasted), <–2 sd on NCHS/CDC reference for weight for height 

• Overall undernutrition (underweight), <–2 sd on NCHS/CDC reference for weight for age 

Key independent variables 

The key independent variables are the length of the preceding birth–to–conception interval, the mother’s 

age at the child’s birth, and the child’s birth order. 

The length of the preceding birth–to–conception interval is measured as the number of months between 

the date of the conception of the child under study (index child) and the date of the immediately preceding 

birth, if any, to the mother. The interval is calculated as the difference in birth dates (year and month) 

between the birth of the preceding child and of the index child, subtracting the duration of gestation of the 

index child where available. Where not available, nine months of gestation were assumed. These 

categories correspond to the categories that were agreed upon by the World Health Organization (WHO) 

review team members and other researchers to provide harmonized results (< 6, 6–11, 12–17, 18–23, 24–

29, 30–35, 36–47, 48–59, 60–95, 96+ months, first births, and missing). For the calculation of the 

population attributable risk (PAR), the following condensed categories are used: <36 months, 36+ 

months, first births, and missing. 

Maternal age at the child’s birth is calculated using the mother’s age at the time of interview and the date 

of the child’s birth. Maternal age is then grouped into five categories: < 18, 18–24, 25–34, 35–39, and 40 

years or older. For the calculation of the PAR, the following two sets of condensed categories are used: < 

18 or 40+ years and 18–39 years; <18 or 35+ years and 18–34 years. 

Birth order is examined using five categories in the univariate and bivariate analyses: first, second, third–

fourth, fifth–sixth, and seventh and higher. Note that this variable is a count of all live births the mother 

had before the index child rather than a count of all pregnancies, since the standard DHS does not include 

a full pregnancy history. For the multivariate analysis, first and second order births are combined into a 

single category, because the model also includes preceding birth interval, which has a separate category 

for first births. For the calculation of PAR, the following condensed categories are used: first–third birth 

order and fourth–plus order. 

To examine potential interactions between the three key independent variables, two additional summary 

indicators are used. The first indicator examines each possible combination of the three exposure 

variables, separately: no extra risk; unavoidable first–birth risk; single risk spacing < 24 months; single 

risk spacing 24–35 months; single risk age < 18; single risk age 40+; single risk order 4+; double risk 

spacing < 24 months and order 4+; double risk spacing 24–35 months and order 4+; double risk first birth 

and age < 18; double risk first birth and age 40+; double risk order 4+ and age < 18; double risk order 4+ 

and age 40+; double risk spacing < 24 months and age < 18; double risk spacing 24–35 months and age < 

18; double risk spacing < 24 months and age 40+; double risk spacing 24–35 months and age 40+; 3–way 

risk spacing < 24 months, order 4+ and age < 18; 3–way risk spacing < 24 months, order 4+, and age 40+; 

3–way risk spacing 24–35 months, order 4+, and age < 18; 3–way risk spacing 24–35 months, order 4+, 

and age 40+; and missing. The second indicator is a summary of the first, with six categories: no extra 

risk, unavoidable first–birth risk, any single risk, any double risk, any 3–way risk, and missing. 

Both bivariate and multivariate designs are used. The multivariate analysis is based on the pooled data for 

all 45 surveys together for each of the mortality age ranges. The coefficients are exponentiated to give the 

relative risk ratios. The 95 percent confidence interval of the relative risk ratio is calculated by adding or 

subtracting 1.96 times the summary standard error from the coefficient before exponentiation. 
9 

Control variables in the multivariate analysis 

A number of factors could potentially confound the relationship between the three key independent 

variables (preceding birth–to–conception interval, maternal age, and birth order) and young child 

mortality. These have been cited by a number of authors [for example, see (Winikoff 1983)]. Birth–

specific confounders include the multiplicity of the birth, the sex of the child, use of health care services, 

breastfeeding, and wantedness of the birth. Mother–specific confounders include socioeconomic status 

and type of area of residence. To control for any potential confounding due to multiplicity of birth, the 

study population is restricted to singleton births. To control for potential confounding by other 

characteristics of the birth and mother, variables representing these factors have been used in the multiple 

regression analyses. A slightly modified list of controls are included in multivariate models for the 

different outcomes. As mentioned above, models examining death within the first year include variables 

on maternal and birth care; models examining child mortality, under–five mortality, and nutritional status 

do not. 

Male children have higher mortality in most cultures. In others, neglect and infanticide may invert this 

biological relationship. In these cultures, birth intervals also may be associated with the child’s sex as 

families strive to meet their gender goals. 

The use of health care services can be related to both mortality, through preventive and curative services, 

and availability and use of contraception (Potter 1988). Information is not available for most of the births 

from the surveys on the use of contraception between births. Therefore, type of prenatal care provider, 

delivery attendant, and number of tetanus toxoid vaccinations during pregnancy are used as measures of 

access to both health services for children and contraception. Moreover, these variables are more directly 

related to perinatal and neonatal mortality.3

Breastfeeding provides a potentially confounding link between mortality and birth intervals. External 

factors such as household environment can raise the mortality of both the index child and the next older 

sibling. The death of the older sibling will cut short the duration of breastfeeding and postpartum 

amenorrhea, leading to an increased risk of a short birth interval. Taking account of the survival of the 

preceding child controls for the breastfeeding–amenorrhea effect and for the external mortality 

relationships. However, the risk of death of the preceding child can also be raised by its short subsequent 

interval (Hobcraft, McDonald, and Rutstein 1983) so that controlling for any death may result in an over–

correction. The death of the preceding child can only affect the preceding birth interval if the death occurs 

before the conception of the index child. To avoid over–correction, only deaths of the preceding child 

before the index child’s conception will be controlled in these analyses. 

An unwanted child, especially one due to contraceptive failure, may suffer more neglect than wanted 

children. To control for these effects, the wantedness of the child4

 and whether the child resulted from a 

failure of contraception are used as controls in the analyses. Because these variables are only available for 

births that occurred in the five years preceding the survey, they are used for the neonatal and infant and 

nutritional status analyses, but they cannot be used for under–five mortality analyses because those 

analyses are based on children born in the 15 years prior to the surveys. Moreover, information on births 

 

3

 To avoid reverse causality, other vaccinations cannot be used for neonatal and infant mortality, because children 

may die before they are of age to get the vaccination. Infant deaths usually consist of about half neonatal and half 

post-neonatal deaths, but the majority of post-neonatal mortality comes in the early months and, therefore, many 

deaths occur before the age at which vaccinations for DPT, polio, and measles are given. Indeed, in Latin America, 

measles vaccinations are given after the first year of life. 

4

 Whether the mother wanted the pregnancy to occur at the time it did, wanted the pregnancy later, or wanted no 

more pregnancies. 
10 

resulting from a failure of contraception is not available for countries with low contraceptive prevalence 

nor in several other surveys.5

Access to health services and to contraceptives, physical and social environments, and socioeconomic 

status are associated with both child mortality and the spacing of births. To control for these effects, five 

variables are used in the analyses: mother’s level of education (none, primary, secondary, or higher), type 

of area of residence (urban or rural), wealth (quintile of DHS Wealth Index [Filmer and Pritchett 2001; 

Rutstein and Johnson 2004)], and type of drinking water supply and type of toilet facility.6

 Appendix 

Table 1 shows the distribution of births by control variables used in the multivariate analyses. 

Control variables: 

Demographic controls 

• Pregnancy duration 

• Sex of index child 

• Death of the preceding child prior to the conception of the index child 

• Outcome of preceding pregnancy (live birth or stillbirth) 

Behavioral controls 

• Wantedness (time wanted pregnancy or whether birth wanted at all) 

• Pregnancy result of contraceptive failure of any method 

Health care controls 

• Prenatal care provider 

• Prenatal initial checkup month of pregnancy 

• Number of prenatal tetanus toxoid vaccinations 

• Delivery care provider 

Socioeconomic and environmental controls 

• Urban–rural residence 

• Mother’s level of education 

• DHS Wealth Index quintile 

 

5

 There are no calendar data on failure from Albania, Benin, Bolivia, Cameroon, Congo DR, Dominican Republic, 

Ghana, Guyana, Liberia, Lesotho, Madagascar, Mali, Namibia, Niger, Nigeria, Pakistan, Philippines, Sao Tome and 

Principe, Sierra Leone, Swaziland, Timor-Leste, and Zambia. 

6

 The absence of the father (or mother’s spouse/partner) also may be related to both child mortality and birth 

intervals. Children whose father is absent may have lessened resources for child care and health service utilization. 

Birth intervals also may be longer if the mother has less frequent sexual relations due to the absence. However, in 

DHS surveys it is not possible to ascertain the father’s presence in the household at the time of death for children 

who have died, nor is it possible to determine whether the child was living away from home at the time of death. 
11 

• Source of drinking water 

• Refrigerator 

• Toilet facility 

Analysis methodology 

The analyses were performed using SPSS 20.0.0 software. 

Infant and child mortality 

Bivariate relationships are studied using life tables for each category of the independent variables for each 

survey separately and for all the surveys pooled together. The life tables were calculated using the 

Survival procedure of SPSS. (These results will be available in a separate appendix upon request.) 

Unadjusted risk ratios for the pooled data set were calculated using the Cox regression procedure. 

To ascertain risk ratios controlling for confounding factors, i.e., adjusted risk ratios, Cox regression 

analysis is employed. Cases are individual children, alive or not. The dependent variable is the survival of 

the index children during the mortality age interval of interest for children surviving to the beginning of 

the age interval. The principal independent variables are the preceding birth–to–conception interval, the 

mother’s age at the child’s birth, and the child’s birth order. First births are included as a separate 

category in the birth interval variable as are the few intervals with missing data. The interval 36–47 

months is used as the reference category. For maternal age, women ages 18 to 24 years are used as the 

reference category, and for birth order, first and second births are used as the reference category. 

The control variables given above are used to control for potentially confounding relationships. Missing 

values for each independent variable are included as separate categories. The DHS surveys do not permit 

missing data on survival or age at death. The results presented are exponentiated coefficients to obtain the 

adjusted risk ratios.7

 

For the analyses of current nutritional status, odds ratios are used as the form of the dependent variable. 

To ascertain adjusted odds ratios, binary logistic analysis is employed. Cases for current nutritional status 

are living children. Children with missing values on the dependent variables are omitted from that 

analysis. The principal independent variables are the preceding birth interval, the mother’s age at the 

child’s birth, and the child’s birth order, calculated as described above for the mortality analyses. The 

results are presented in the form of unadjusted and adjusted odds ratios. 

DHS Data Used in the Study 

The data used in this study come from all 45 national surveys in The DHS Program with field work that 

took place between 2006 and 2012. This program of surveys in developing countries started in 1984 and 

is financed principally by USAID. The surveys in The DHS Program are based on scientifically selected 

 

7

 In the 52-country study (Rutstein 2008), analyses were performed on several countries, incorporating the sample 

design into the multivariate analysis (using svylogit in STATA 9.1). Account was taken of both the clustering of the 

cases by sampling units and sample stratification with the result that a slight reduction in the estimated confidence 

interval ensued. Due to the laboriousness of hand-combining sample clusters when there were no deaths in the 

mortality age range, the more conservative approach of ignoring sample clustering and stratification was taken in the 

current study. Note that although clustering would seem to increase the estimated standard errors, appropriate 

stratification in the sample design and inclusion of the major differences between clusters as control variables in the 

model actually removed the effects of clustering. 
12 

samples of households and women of reproductive age to produce nationally representative data on 

fertility, infant and child mortality, child and reproductive health, nutritional status, family planning, and 

many other health–related issues. In many countries, men of reproductive age are also are interviewed. 

Each country survey is conducted by individual country survey organizations with technical assistance in 

design, sampling, training, fieldwork, data processing, tabulation, and report generation provided by ICF 

International.8

The household section of the DHS collects general household information such as location, possessions, 

and services. A roster of household members collects information on sex, age, relationship to the head, de 

facto and de jure status, and educational level. Women between the ages of 15–49 years, inclusive, who 

slept in the dwelling the night before interview, are selected for interviewing with an individual 

questionnaire.9

The individual women’s questionnaire contains a complete birth history with birth dates, sex, multiplicity 

of birth, survival status, and age at death if not surviving for each child. In some countries, a month–by–

month reproductive calendar of the preceding five years gives information on pregnancies by duration and 

type of termination. For each child under five years of age, information is collected on prenatal and 

delivery care, birth weight and size, vaccinations received, feeding and breastfeeding, and morbidity 

status and treatment. Nutritional and anemia status of the women and children under five years is 

ascertained through anthropometric measurement and finger pricks, respectively. 

All interviews are conducted face–to–face by specially trained women interviewers. Anthropometric 

measurements are taken using internationally standard height boards and UNICEF scales. Specially 

trained staff members–in many cases, public health nurses–carry out the anthropometric measurements. 

The quality of the DHS data is among the highest for data on births and infant and child deaths in the 

developing countries [see (Curtis 1995; Pullum 2006; Sullivan, Bicego, and Rutstein 1990)]. There is 

evidence for a small amount of digit preference for 12 months in the declaration of age at death, so that 

infant and post–neonatal rates may be understated and child mortality may be overstated by up to 5 

percent. No effect on neonatal or under–five–years mortality rates has been found. Some evidence exists 

for transference of births to a year earlier in order to avoid asking a long health section for young 

children. For most surveys, this boundary is at five calendar years prior to the survey. In other surveys, 

the health section eligibility boundary is three or four calendar years prior to the survey. Because most of 

the questions are for children living at the time of the survey, the effect of the transference would be to 

slightly lower mortality rates for short preceding birth intervals but only for children born in the calendar 

year after the boundary. For a more in–depth evaluation of later DHS surveys, see Pullum (2006) who 

states that “there is virtually no evidence of heaping on age of child” and that “small deviations from a 

uniform distribution tend not to be at final digits 0 and 5.” With regard to heaping on birth intervals, 

Pullum states, “There is no evidence of heaping on multiples of six months.” The five surveys that show 

any irregularities took place before 2000 and are not part of the current analysis data set. 

The 45 surveys selected for this analysis represent the following countries: Albania, Armenia, Azerbaijan, 

Bangladesh, Benin, Bolivia, Burkina Faso, Burundi, Cambodia, Cameroon, Colombia, Congo DR, 

Dominican Republic, Egypt, Ethiopia, Ghana, Guyana, India, Indonesia, Jordan, Kenya, Lesotho, Liberia, 

 

8

 The DHS project originally began at Westinghouse Corporation’s Institute for Resource Development which was 

acquired by Macro Systems, Inc., later renamed Macro International, Inc. Opinion Research Corporation acquired 

Macro International in 1999. InfoUSA bought Macro International in 2006 and subsequently sold the company to 

ICF International, and the Macro International name was abandoned. 

9

 In some countries of the Near East and Asia, only ever-married women are considered eligible for interview. 
13 

Madagascar, Malawi, Mali, Mozambique, Namibia, Nepal, Niger, Nigeria, Pakistan, Peru, Philippines, 

Rwanda, Sao Tome and Principe, Senegal, Sierra Leone, Swaziland, Tanzania, Timor–Leste, Uganda, 

Ukraine, Zambia, and Zimbabwe (Table 1). These 45 surveys are all those that took place between 2006 

and 2012. All available surveys in the DHS program carried out between 2006 and 2012 are included in 

the analysis. However, three surveys did not include anthropometry and will not be used in the nutrition 

status analysis: Indonesia, Philippines, and Ukraine. 

Table 1. List of surveys, by year 

Year Countries 

2005–06 India 

2006 Azerbaijan, Benin, Mali, Niger 

2006–07 Namibia, Pakistan, Swaziland 

2007 Congo DR, Dominican Republic, Indonesia, Jordan, Liberia, Ukraine, Zambia 

2008 Bolivia, Egypt, Ghana, Nigeria, Philippines, Sierra Leone 

2008–09 Albania, Kenya, Madagascar, Sao Tome and Principe 

2009 Guyana, Lesotho, Timor–Leste 

2010 Armenia, Burkina Faso, Burundi, Cambodia, Colombia, Malawi, Rwanda, Tanzania 

2010–11 Senegal, Zimbabwe 

2011 Bangladesh, Cameroon, Ethiopia, Mozambique, Nepal, Uganda 

2012 Peru 

Creation of the Pooled Data Set 

Child and pregnancy–related data for singleton births in the 15 years preceding the survey were extracted 

from each survey using ISSA and entered into an SPSS .sav file. A pooled data set was created from the 

individual survey .sav files with 1,227,161 cases (births). 

15 

Results 

Univariate Results 

Table 2 shows the distributions of preceding birth–to–conception intervals of births in the period 0–179 

months prior to the surveys. Because of the large sample sizes, 15 percent of the births are from India and 

nearly one in three (30 percent) is from India, Colombia, Indonesia, Malawi, and Burkina Faso. Of all the 

births considered, slightly more than one quarter were first births, based on the unweighted average. 

Among second and higher order births, the mean number of months since the preceding birth was 37.8 

months with a median of 31 months. Very short intervals of fewer than 12 months between a birth and the 

following conception accounted for more than 17 percent of the intervals of second or higher order births. 

While more than 37 percent of birth–to–conception intervals were fewer than 18 months in duration, more 

than another 28 percent occurred with durations of 18 to 30 months, resulting in about two thirds of 

second and higher order births being at durations of fewer than 30 months. 

Analyses using the birth–to–conception interval depend on the respondent’s knowledge of the birth dates 

and length of gestation of her children. The DHS questionnaire requests the month and year of each birth. 

For living children, the child’s age in years is also requested. The DHS procedures call for imputing the 

month and year of birth when the respondent could not give the information. The procedure depends on 

the type of information given in the birth history. Croft [no date] provides a description of the process. 

For 0.1 percent of the live births, the interval is missing. The survey with the most missing data on 

duration of intervals is Senegal 2010–11 where, at most, 0.04 percent is missing. 

The accuracy of birth spacing intervals depends on the accuracy of the birth dates of children. For all 

births 0 to 179 months prior to the surveys, almost 97 percent had a birth date reported in years and 

months, and for 2 percent, the month needed to be imputed. Only four countries had less than 90 percent 

of births with year and month of birth: Benin (20 percent), Niger (20 percent), Pakistan (36 percent), and 

Senegal (25 percent). Imputation of the interval would normally weaken the relationships with mortality 

and nutritional status because the interval is randomly assigned within specified limits. For example, 

births with true shorter intervals and thus higher mortality and malnutrition proportions would then be 

imputed to have both short and long intervals, reducing the observed strength of the relationships. 

Imputation intervals can be handled in a couple of ways. One way would be to include a variable in 

multivariate analysis that indicates whether that child had an imputed interval or not. This procedure 

would allow for a greater number of cases (reducing standard errors) and an easy vision of the effect of 

the imputation. Another way is to use only non–imputed cases, which, although a cleaner procedure, may 

result in larger standard errors. The second procedure has been adopted for the analyses in this paper. 

It has been postulated that premature births are a confounding factor in the analysis of neonatal, post–

neonatal, and infant mortality rates by shortening the birth–to–birth interval through a shortened length of 

gestation. Because premature births are known to have high rates of mortality, the mortality effects of 

short birth intervals (as opposed to short pregnancy intervals) may be biased upwards, since they would 

contain a disproportionately high number of premature births. The shorter the interval, the more likely 

that the proportion of premature births is higher. The analyses that have shown to be most affected are 
16 

those with birth intervals of under 12 or under 15 months. The length of gestation is not available for 

survey data. In this case it is assumed that the gestation was nine months.10 

 

10 The earlier article examined the potential effect on the results that adjusting for gestational length would have on 

the classification of births into birth interval categories. That examination found that, at most, about 0.2 percent of 

births had been shifted into a longer birth interval due to the assumption of a nine-month gestation rather than actual 

gestation. In the shortest birth interval, only 0.1 percent of births had been misclassified. Thus, even if premature 

births have much higher rates of mortality, the combined effect is quite small given that 99.9 percent will be 

correctly classified. 
Table 2. Distribution of births 0 to 179 months prior to survey by duration of preceding birth–to–conception interval, 45 DHS surveys, 

2006–2012 

Survey 

Preceding birth–to–conception interval in months (%) 

Mean Median N < 6 6-11 12-17 18-23 24-29 30-35 36-47 48-59 60-95 96+ 

First 

births Total 

Albania 2008-09 2.3 6.2 8.5 7.5 7.7 6.0 10.5 7.3 8.3 2.5 33.1 100.0 45.7 40.0 6,867 Armenia 2010 4.4 9.5 6.9 5.9 4.7 4.0 6.1 3.9 5.4 3.7 45.5 100.0 43.6 33.0 4,167 Azerbaijan 2006 7.2 12.6 10.3 8.1 5.4 3.5 5.0 3.0 4.7 1.5 38.8 100.0 35.0 27.0 7,564 Bangladesh 2011 2.8 5.0 8.7 7.6 7.7 5.6 9.5 6.9 9.3 3.4 33.3 100.0 47.7 40.0 27,377 

Benin 2006 2.8 7.1 15.1 15.5 13.4 8.2 8.2 3.7 3.1 1.0 22.0 100.0 35.9 32.0 39,544 Bolivia 2008 5.1 9.5 15.6 11.5 7.4 4.9 6.7 4.3 6.2 3.1 25.9 100.0 39.5 30.0 26,730 Burkina Faso 2010 2.0 6.9 14.4 15.8 13.7 9.8 9.2 3.9 3.1 0.6 20.5 100.0 36.2 33.0 40,092 Burundi 2010 4.8 8.0 16.6 15.2 12.8 7.3 8.1 3.1 2.3 0.5 21.3 100.0 33.5 30.0 18,799 Cambodia 2010 3.5 5.8 11.8 9.7 9.1 6.3 9.6 5.4 6.8 2.5 29.4 100.0 42.4 35.0 23,438 Cameroon 2011 5.3 8.7 15.7 14.0 9.4 6.5 7.7 3.8 3.9 1.3 23.7 100.0 35.7 30.0 28,932 

Colombia 2010 3.1 6.6 8.1 6.5 5.3 4.0 6.6 5.3 9.4 6.5 38.4 100.0 52.6 40.0 49,404 

Congo DR 2007 5.7 8.1 18.0 14.5 11.5 6.3 7.1 3.0 3.1 1.2 21.5 100.0 34.2 29.0 21,330 

Dominican Republic 

2007 6.3 9.6 9.9 8.2 6.3 5.0 7.2 4.9 6.5 3.0 33.0 100.0 41.3 32.0 33,076 

Egypt 2008 4.6 6.9 10.6 9.8 9.2 6.2 8.8 5.4 6.2 1.8 30.6 100.0 40.4 34.0 29,213 Ethiopia 2011 6.3 8.6 15.9 14.0 11.7 7.2 8.3 3.7 3.5 1.0 20.0 100.0 34.6 30.0 33,168 

Ghana 2008 2.6 5.7 11.7 10.9 9.1 7.9 11.6 6.0 6.9 2.3 25.2 100.0 43.0 37.0 7,547 Guyana 2009 6.5 9.1 10.7 8.7 6.7 5.0 6.7 4.1 8.0 4.0 30.4 100.0 43.2 32.0 6,025 India 2005–06 6.5 9.6 16.3 10.8 8.7 5.4 6.7 3.3 3.1 0.8 28.7 100.0 33.3 28.0 177,993 

Indonesia 2007 2.8 4.6 6.9 6.0 5.5 4.4 8.4 6.9 12.8 6.4 35.2 100.0 55.9 48.0 48,014 Jordan 2007 7.6 14.0 15.1 10.5 7.9 5.7 7.1 4.4 4.5 1.0 22.0 100.0 33.9 28.0 27,230 Kenya 2008–09 4.6 8.6 14.5 12.6 9.7 6.0 7.9 4.3 5.2 1.7 24.9 100.0 37.6 31.0 15,448 

Lesotho 2009 2.0 3.0 6.6 8.3 9.3 6.7 10.4 6.0 8.3 3.1 36.3 100.0 48.3 41.0 9,124 Liberia 2007 4.7 7.3 13.3 12.2 9.1 6.9 9.2 5.0 6.6 2.3 23.5 100.0 40.2 33.0 14,573 Madagascar 2008–09 5.8 10.1 16.9 12.5 8.4 6.1 7.4 3.8 4.5 1.4 23.3 100.0 35.4 29.0 35,352 

(Continued...) 

17 
Table 2. – Continued

Survey 

Preceding birth-to-conception interval in months (%) 

Mean Median N < 6 6-11 12-17 18-23 24-29 30-35 36-47 48-59 60-95 96+ 

First 

births Total 

Malawi 2010 3.3 6.3 13.4 13.7 12.7 8.0 9.9 4.4 3.7 1.0 23.5 100.0 37.3 33.0 49,925 Mali 2006 5.4 9.9 21.2 15.1 10.4 5.9 6.5 3.0 2.6 0.7 19.4 100.0 32.3 28.0 37,501 Mozambique 2011 3.3 5.9 14.0 14.6 11.6 7.3 8.4 4.3 4.6 1.7 24.3 100.0 38.4 32.0 28,435 

Namibia 2006–07 3.0 4.7 9.7 10.2 8.0 6.1 8.9 6.0 8.1 3.4 32.1 100.0 45.7 37.0 12,955 Nepal 2011 3.3 7.7 13.8 10.7 8.9 6.1 8.4 4.3 4.4 1.2 31.1 100.0 37.6 32.0 17,031 Niger 2006 6.5 10.1 22.0 14.4 11.1 5.8 6.7 3.1 2.2 0.6 17.6 100.0 31.7 27.0 26,808 Nigeria 2008 5.8 9.6 19.3 13.9 10.2 6.2 6.7 3.2 3.4 1.2 20.6 100.0 33.8 28.0 70,621 Pakistan 2006–07 12.1 12.7 18.7 11.1 8.2 4.8 6.2 3.3 2.6 0.6 19.8 100.0 30.2 25.0 26,513 Peru 2012 1.4 4.8 8.5 7.9 6.0 4.7 7.9 6.0 11.1 7.1 34.7 100.0 55.3 44.0 25,753 Philippines 2008 6.3 11.5 13.0 9.6 7.1 4.9 6.6 4.0 5.9 2.5 28.7 100.0 38.0 29.0 18,233 Rwanda 2010 4.0 8.3 16.4 14.8 11.3 7.0 7.4 3.3 3.3 1.0 23.1 100.0 34.9 30.0 23,921 Sao Tome and Principe 

2008–09 2.3 4.7 10.4 10.5 9.2 7.7 11.4 6.6 8.2 3.0 25.9 100.0 45.4 38.0 4,652 

Senegal 2010–11 4.2 8.3 15.3 14.0 10.5 6.3 8.1 4.2 3.9 1.3 23.8 100.0 36.2 31.0 28,149 

Sierra Leone 2008 4.6 7.0 16.0 11.5 10.1 5.9 8.3 4.8 5.3 2.1 24.3 100.0 38.5 32.0 16,041 Swaziland 2006–07 2.6 5.8 12.2 11.1 7.6 6.3 9.2 5.6 7.2 2.6 29.7 100.0 43.1 35.0 7,300 Tanzania 2010 2.6 6.1 14.8 14.9 11.6 7.7 8.7 4.5 4.6 1.5 22.9 100.0 38.2 33.0 20,454 Timor-Leste 2009 5.3 12.1 20.3 15.8 9.5 5.6 6.0 3.2 2.8 1.0 18.3 100.0 32.4 27.0 26,507 Uganda 2011 6.1 10.4 19.2 16.3 10.1 6.1 6.1 2.9 3.1 0.8 18.7 100.0 32.6 28.0 20,733 Ukraine 2007 1.7 3.6 3.2 3.0 2.4 2.3 4.3 4.1 8.7 7.1 59.7 100.0 65.4 55.0 3,855 Zambia 2007 3.4 6.4 14.2 16.6 13.2 6.9 8.4 3.6 3.5 1.0 22.8 100.0 36.1 32.0 15,484 Zimbabwe 2010–11 1.6 3.1 6.1 8.1 8.5 7.5 11.7 8.0 8.7 2.9 33.7 100.0 48.8 43.0 13,405 Total N 4.9 8.3 14.4 11.9 9.4 6.1 7.8 4.3 5.0 1.9 26.2 100.0 37.8 31.0 1,227,151 

Note: Percent distributions are based on weighted cases for all individual countries. The total percent distribution, however, is based on unweighted cases, because the application of standard individual country weights is not meaningful in the pooled sample and analyses using the pooled data are unweighted. Ten unweighted cases with missing information on the length of preceding interval are excluded. 

18 
19 

Table 3 lists the distributions of mother’s age at child’s birth in grouped ages in the period 0–179 months 

prior to the surveys. Of all births considered, slightly more than 8 percent occurred to mothers of less than 

18 years of age, based on the unweighted average. Countries with10 percent or more births in the age 

group less than 18 years include Bangladesh, Cameroon, Colombia, the Dominican Republic, India, 

Madagascar, Mali, Mozambique, Niger, Sierra Leone, and Swaziland. Almost 10 percent of births 

occurred to mothers ages 35 and older. Countries with 3 percent or more births in ages 40 and older 

include Burundi, Congo DR, Ghana, Liberia, Nigeria, Rwanda, and Timor–Leste. Overall, almost one in 

five births occurred at less favorable mothers’ ages. The mean age at birth was 25.5 years. In 16 of the 45 

countries, one fifth or more of births occurred at less favorable ages of the mother. 

Table 3. Distribution of births 0 to 179 months prior to survey by the mother’s age at child’s birth, 

45 DHS surveys, 2006–2012 

Survey 

Mother’s age at child’s birth in years (%) 

< 18 18-24 25-34 35-39 40+ Total Mean Median N 

Albania 2008–09 1.4 36.5 55.5 6.0 0.6 100.0 26.4 26.0 6,867 

Armenia 2010 1.8 57.8 36.3 3.5 0.6 100.0 24.4 23.0 4,167 

Azerbaijan 2006 3.0 49.1 43.3 4.2 0.4 100.0 25.0 24.0 7,564 

Bangladesh 2011 19.7 45.9 29.8 3.9 0.6 100.0 22.8 22.0 27,377 

Benin 2006 8.2 39.4 42.2 8.0 2.2 100.0 25.7 25.0 39,544 

Bolivia 2008 7.4 37.0 43.4 9.7 2.5 100.0 26.2 26.0 26,730 

Burkina Faso 2010 7.2 38.8 41.6 9.7 2.7 100.0 26.1 25.0 40,092 

Burundi 2010 3.4 35.1 45.9 11.9 3.7 100.0 27.3 27.0 18,799 

Cambodia 2010 3.3 37.6 46.5 10.2 2.4 100.0 26.7 26.0 23,438 

Cameroon 2011 11.3 40.0 38.8 7.9 2.0 100.0 25.1 24.0 28,932 

Colombia 2010 10.9 41.5 39.1 7.1 1.5 100.0 24.9 24.0 49,404 

Congo DR 2007 7.9 37.7 41.2 10.0 3.2 100.0 26.2 25.0 21,330 

Dominican 

Republic 

2007 12.0 45.7 37.0 4.6 0.7 100.0 24.0 23.0 33,076 

Egypt 2008 4.1 41.8 45.8 7.1 1.2 100.0 25.8 25.0 29,213 

Ethiopia 2011 9.0 38.5 41.1 8.9 2.6 100.0 25.8 25.0 33,168 

Ghana 2008 6.3 34.4 46.4 9.8 3.1 100.0 26.6 26.0 7,547 

Guyana 2009 9.0 42.4 39.3 8.0 1.3 100.0 25.2 24.0 6,025 

India 2005–06 10.9 51.9 33.4 3.3 0.5 100.0 23.5 23.0 177,993 

Indonesia 2007 4.7 36.7 47.8 8.9 1.9 100.0 26.4 26.0 48,014 

Jordan 2007 1.7 32.8 53.3 10.4 1.8 100.0 27.3 27.0 27,230 

Kenya 2008–09 9.3 41.8 39.2 7.7 2.1 100.0 25.2 24.0 15,448 

Lesotho 2009 7.3 45.1 37.1 8.2 2.3 100.0 25.3 24.0 9,124 

Liberia 2007 9.8 37.2 39.4 10.2 3.4 100.0 26.0 25.0 14,573 

Madagascar 2008–09 10.7 37.9 39.8 9.1 2.6 100.0 25.6 25.0 35,352 

Malawi 2010 9.9 44.2 36.3 7.2 2.3 100.0 24.9 24.0 49,927 

Mali 2006 12.4 38.1 38.5 8.6 2.4 100.0 25.2 24.0 37,501 

Mozambique 2011 11.9 38.7 37.8 8.6 2.9 100.0 25.3 24.0 28,435 

(Continued...)
20 

Table 3. – Continued

Survey 

Mother’s age at child’s birth in years (%) 

< 18 18-24 25-34 35-39 40+ Total Mean Median N 

Namibia 2006–07 7.1 38.0 43.2 9.2 2.4 100.0 26.1 25.0 12,955 

Nepal 2011 8.8 50.5 35.1 4.6 1.0 100.0 24.1 23.0 17,031 

Niger 2006 13.2 38.7 37.8 8.1 2.2 100.0 25.1 24.0 26,808 

Nigeria 2008 9.9 35.4 42.5 9.1 3.1 100.0 26.0 25.0 70,621 

Pakistan 2006–07 5.1 36.9 47.2 8.8 2.1 100.0 26.4 26.0 26,513 

Peru 2012 6.7 35.9 44.5 10.3 2.6 100.0 26.4 26.0 25,753 

Philippines 2008 3.2 35.5 48.4 10.1 2.7 100.0 27.0 26.0 18,233 

Rwanda 2010 2.0 33.8 48.3 11.9 4.0 100.0 27.6 27.0 23,921 

Sao Tome 

and Principe 

2008–09 7.5 41.5 38.2 10.0 2.8 100.0 25.8 25.0 4,652 

Senegal 2010–11 9.0 36.7 43.3 8.8 2.2 100.0 25.9 25.0 28,157 

Sierra Leone 2008 13.0 38.3 38.9 7.7 2.1 100.0 25.0 24.0 16,041 

Swaziland 2006–07 11.1 41.0 37.9 8.3 1.7 100.0 25.1 24.0 7,300 

Tanzania 2010 8.0 40.1 40.5 8.9 2.4 100.0 25.8 25.0 20,454 

Timor-Leste 2009 2.8 30.1 49.2 13.5 4.4 100.0 28.1 28.0 26,507 

Uganda 2011 9.7 40.3 39.4 8.4 2.2 100.0 25.4 24.0 20,733 

Ukraine 2007 3.7 55.3 37.0 3.5 0.4 100.0 24.3 23.0 3,855 

Zambia 2007 9.7 42.1 38.1 7.7 2.4 100.0 25.2 24.0 15,484 

Zimbabwe 2010–11 8.5 45.5 38.0 6.5 1.5 100.0 24.8 24.0 13,405 

Total N 8.6 40.6 40.9 7.8 2.1 100.0 25.5 25.0 1,227,161 

Note: Percent distributions are based on weighted cases for all individual countries. The total percent distribution, 

however, is based on unweighted cases, because the application of standard individual country weights is not 

meaningful in the pooled sample and analyses using the pooled data are unweighted. 

Analyses using mother’s age at birth depend on the respondent’s knowledge of her and her child’s birth 

dates and/or current ages. The DHS questionnaire requests the month and year of birth of the individual 

respondent as well as her age. If either the year or month of her birth is not known, then an imputation 

procedure is used to estimate the missing data. In the recode data sets, all women are required to have a 

birth date either by response or imputation. A description of the process is given in Croft [no date]. Based 

on the weighted data, for 69 percent of the live births, the mother gave her age as month and year; 17 

percent had the mother’s month of birth missing; and for 12 percent the month and year of the mother’s 

birth were imputed from age. The survey with the most missing mother’s birth date is Bangladesh 2011 

where almost 93 percent of birth dates were based on age alone. In Azerbaijan, Colombia, and Peru no 

imputation was needed. 

First births are considered to have additional risks for both the child and the mother, compared with 

second or third births. Likewise, higher order births invoke higher risks. Table 4 shows the distribution of 

births in months 0–179 prior to the survey by their birth order. As noted above, slightly more than one in 

four births was firstborn, an unavoidable risk if there are to be any children. However, almost one in four 

births was of order five or greater. In 6 of the 45 surveys, more than one third of births are of order five or 

higher. In five surveys, less than 10 percent are so. For all the surveys together, the median birth order is 

three. 
21 

Table 4. Distribution of births 0 to 179 months prior to survey by the child’s birth order, 45 DHS 

surveys, 2006–2012 

Survey 

Birth order (%) 

1 2 3-4 5-6 7+ Total Mean Median N 

Albania 2008–09 33.1 34.9 27.2 3.9 0.9 100.0 2.2 2.0 6,867 

Armenia 2010 45.5 36.3 16.5 1.3 0.4 100.0 1.8 2.0 4,167 

Azerbaijan 2006 38.8 33.8 23.5 3.3 0.6 100.0 2.1 2.0 7,564 

Bangladesh 2011 33.3 26.8 27.2 9.0 3.6 100.0 2.6 2.0 27,377 

Benin 2006 22.0 19.4 29.4 17.7 11.6 100.0 3.5 3.0 39,544 

Bolivia 2008 25.9 21.5 27.2 14.5 10.9 100.0 3.3 3.0 26,730 

Burkina Faso 2010 20.5 18.3 29.1 19.1 12.8 100.0 3.7 3.0 40,092 

Burundi 2010 21.3 18.3 28.9 18.3 13.2 100.0 3.6 3.0 18,799 

Cambodia 2010 29.4 24.2 28.3 12.2 6.0 100.0 2.9 2.0 23,438 

Cameroon 2011 23.7 19.1 27.7 16.8 12.6 100.0 3.5 3.0 28,932 

Colombia 2010 38.4 28.5 24.1 6.2 2.8 100.0 2.3 2.0 49,404 

Congo DR 2007 21.5 18.0 28.0 18.1 14.5 100.0 3.7 3.0 21,330 

Dominican 

Republic 

2007 33.0 27.3 29.7 7.2 2.7 100.0 2.5 2.0 33,076 

Egypt 2008 30.6 25.8 29.5 9.7 4.4 100.0 2.7 2.0 29,213 

Ethiopia 2011 20.0 17.6 27.5 18.6 16.3 100.0 3.9 3.0 33,168 

Ghana 2008 25.2 21.4 30.2 14.9 8.2 100.0 3.2 3.0 7,547 

Guyana 2009 30.4 24.8 28.4 10.7 5.7 100.0 2.8 2.0 6,025 

India 2005–06 28.7 25.6 28.7 11.6 5.4 100.0 2.8 2.0 177,993 

Indonesia 2007 35.2 27.4 25.4 8.0 4.0 100.0 2.5 2.0 48,014 

Jordan 2007 22.0 20.2 31.0 16.7 10.2 100.0 3.4 3.0 27,230 

Kenya 2008–09 24.9 20.9 28.4 15.3 10.5 100.0 3.3 3.0 15,448 

Lesotho 2009 36.3 24.4 25.4 9.9 3.9 100.0 2.6 2.0 9,124 

Liberia 2007 23.5 19.4 27.6 16.5 13.1 100.0 3.5 3.0 14,573 

Madagascar 2008–09 23.3 20.0 28.4 15.9 12.4 100.0 3.5 3.0 35,352 

Malawi 2010 23.5 20.5 29.3 16.2 10.5 100.0 3.4 3.0 49,927 

Mali 2006 19.4 17.2 27.1 18.8 17.5 100.0 4.0 3.0 37,501 

Mozambique 2011 24.3 20.4 29.6 16.2 9.4 100.0 3.3 3.0 28,435 

Namibia 2006–07 32.1 23.8 27.0 11.5 5.7 100.0 2.8 2.0 12,955 

Nepal 2011 31.1 26.3 27.9 10.1 4.6 100.0 2.7 2.0 17,031 

Niger 2006 17.6 16.1 27.0 19.7 19.6 100.0 4.2 4.0 26,808 

Nigeria 2008 20.6 18.2 28.4 17.5 15.3 100.0 3.8 3.0 70,621 

Pakistan 2006–07 19.8 17.9 29.1 18.6 14.7 100.0 3.8 3.0 26,513 

Peru 2012 34.7 26.3 25.1 8.9 5.0 100.0 2.6 2.0 25,753 

Philippines 2008 28.7 22.5 28.1 12.6 8.1 100.0 3.0 2.0 18,233 

Rwanda 2010 23.1 19.4 28.9 17.5 11.1 100.0 3.5 3.0 23,921 

Sao Tome 

and Principe 

2008–09 25.9 22.0 29.0 13.9 9.2 100.0 3.2 3.0 4,652 

Senegal 2010–11 23.8 19.4 28.1 17.3 11.6 100.0 3.5 3.0 28,157 

(Continued...)
22 

Table 4. – Continued

Survey 

Birth order (%) 

1 2 3-4 5-6 7+ Total Mean Median N 

Sierra Leone 2008 24.3 21.3 29.8 15.7 8.9 100.0 3.3 3.0 16,041 

Swaziland 2006–07 29.7 21.2 25.5 13.8 9.8 100.0 3.2 2.0 7,300 

Tanzania 2010 22.9 19.8 28.6 16.7 12.0 100.0 3.5 3.0 20,454 

Timor-Leste 2009 18.3 17.3 30.0 20.3 14.1 100.0 3.8 3.0 26,507 

Uganda 2011 18.7 17.0 27.5 19.3 17.5 100.0 4.0 3.0 20,733 

Ukraine 2007 59.7 31.1 8.0 0.9 0.3 100.0 1.6 1.0 3,855 

Zambia 2007 22.8 19.4 28.6 16.6 12.6 100.0 3.5 3.0 15,484 

Zimbabwe 2010–11 33.7 26.2 27.1 9.3 3.7 100.0 2.6 2.0 13,405 

 

Total N 26.2 22.0 28.0 14.2 9.6 100.0 3.2 3.0 1,227,161 

Note: Percent distributions are based on weighted cases for all individual countries. The total percent distribution, 

however, is based on unweighted cases, because the application of standard individual country weights is not 

meaningful in the pooled sample and analyses using the pooled data are unweighted. 

Children may be subject to multiple fertility behavior risk factors at the same time. Table 5 presents the 

distribution of births in the 15 years preceding the survey by each combination of additional risk. Table 6 

presents a summarization of Table 5 through five categories: no additional risk factors, an unavoidable 

additional risk factor (i.e., a first birth), one additional risk factor, two additional risk factors, and three 

additional risk factors. 

From Table 5, 16 percent of children faced no extra risk and another 19 percent had only the unavoidable 

risk of being firstborn. Other extra–risk categories with substantial percentages of births are a single–risk 

factor for inadequate spacing (fewer than 24 months and 24–35 months), a single–risk factor for births of 

order four or greater, and a double–risk factor for both inadequate spacing and high birth order, each of 

which has about 12 percent of the births. 
Table 5. Distribution of births 0 to 179 months prior to survey by maternal fertility–related risk factors, 45 DHS surveys, 2006–2012 

Survey 

Extra risk due to fertility pattern (%) 

No 

extra 

risk 

Unavoidable 

firstbirth 

risk 

Single 

risk 

spacing 

<24 

mos. 

Single 

risk 

spacing 

24-35 

mos. 

Single 

risk 

age 

<18 

Single 

risk 

age 

40+ 

Single 

risk 

order 

4+ 

Double 

risk 

spacing 

<24, 

order 

4+ 

Double 

risk 

spacing 

24-35, 

order 

4+ 

Double 

risk 

firstbirth, 

age 

<18 

Double 

risk 

order 

4+, 

age 

40+ 

Double 

risk 

spacing 

<24 

and age 

<18 

Double 

risk 

spacing 

24-35 

and age 

<18 

3-way 

risk 

spacing

<24, 

order 

4+, 

age 

<18 

3-way 

risk 

spacing 

<24, 

order 

4+, 

age 

40+ 

3-way 

risk, 

spacing 

24-35, 

order 

4+, 

age 

40+ Total N 

Albania 2008–09 31.8 31.7 10.2 12.5 0.0 0.1 6.1 2.9 2.7 1.3 0.4 0.1 0.0 0.0 0.0 0.0 100.0 6,867 Armenia 2010 21.8 44.0 16.6 10.2 0.0 0.3 3.2 0.9 1.0 1.5 0.1 0.2 0.0 0.0 0.1 0.1 100.0 4,167 Azerbaijan 2006 15.5 36.0 22.0 13.1 0.0 0.1 4.4 2.8 2.7 2.6 0.1 0.3 0.0 0.0 0.0 0.1 100.0 7,564 Bangladesh 2011 26.5 17.1 5.5 8.7 0.5 0.0 11.3 4.6 6.0 16.2 0.4 1.6 1.4 0.0 0.1 0.1 100.0 27,377 Benin 2006 13.8 15.7 6.6 13.3 0.2 0.1 15.1 9.4 15.7 6.2 1.2 0.9 0.8 0.0 0.2 0.7 100.0 39,544 Bolivia 2008 15.3 19.7 10.1 10.3 0.1 0.2 11.6 10.5 12.6 6.2 1.4 0.9 0.3 0.0 0.3 0.5 100.0 26,730 Burkina Faso 2010 14.2 14.3 6.0 13.0 0.1 0.0 16.8 9.1 16.8 6.2 1.7 0.4 0.5 0.0 0.3 0.7 100.0 40,092 Burundi 2010 11.3 18.4 9.1 13.2 0.0 0.0 14.2 10.4 16.4 2.9 2.1 0.3 0.2 0.0 0.6 1.0 100.0 18,799 Cambodia 2010 20.6 26.3 8.1 11.7 0.0 0.3 13.1 5.9 8.6 3.0 1.3 0.2 0.1 0.0 0.2 0.5 100.0 23,438 Cameroon 2011 12.3 15.1 7.7 11.8 0.2 0.1 13.7 11.9 14.2 8.6 1.1 1.3 1.1 0.1 0.4 0.5 100.0 28,932 Colombia 2010 26.0 28.8 8.5 8.3 0.1 0.5 7.2 4.4 4.4 9.5 0.7 0.9 0.4 0.0 0.1 0.1 100.0 49,404 Congo DR 2007 11.5 15.3 8.2 11.7 0.3 0.1 12.9 12.7 16.6 6.2 1.4 0.8 0.6 0.1 0.6 1.0 100.0 21,330 Dominican Republic 2007 21.5 23.4 12.5 10.8 0.2 0.2 7.6 6.5 5.0 9.6 0.3 1.7 0.6 0.0 0.1 0.1 100.0 33,076 Egypt 2008 19.5 27.3 10.8 13.5 0.0 0.1 12.4 5.0 6.3 3.3 0.8 0.5 0.2 0.0 0.1 0.1 100.0 29,213 Ethiopia 2011 11.8 13.3 7.9 10.6 0.3 0.0 15.7 12.9 16.4 6.7 1.4 1.1 0.8 0.0 0.4 0.8 100.0 33,168 Ghana 2008 21.0 19.7 6.2 10.4 0.1 0.1 16.0 6.9 10.4 5.5 2.1 0.4 0.2 0.0 0.3 0.5 100.0 7,547 Guyana 2009 18.9 23.2 11.5 10.2 0.1 0.2 11.1 7.9 6.9 7.2 0.6 1.2 0.5 0.0 0.1 0.2 100.0 6,025 India 2005–06 14.7 20.6 12.3 13.4 0.2 0.0 8.5 9.7 9.5 8.1 0.3 1.7 0.8 0.0 0.1 0.1 100.0 177,993 Indonesia 2007 29.3 31.0 6.2 7.4 0.0 0.3 10.9 3.9 4.7 4.2 1.1 0.3 0.2 0.0 0.1 0.3 100.0 48,014 Jordan 2007 9.1 20.4 17.6 10.5 0.0 0.0 16.1 11.0 11.8 1.5 1.2 0.2 0.1 0.0 0.2 0.3 100.0 27,230 Kenya 2008–09 15.2 17.4 8.6 11.6 0.3 0.1 13.6 9.7 12.5 7.5 1.0 0.9 0.6 0.0 0.4 0.5 100.0 15,448 Lesotho 2009 24.4 29.4 4.9 10.0 0.1 0.2 13.2 2.6 5.7 6.9 1.7 0.3 0.1 0.0 0.1 0.4 100.0 9,124 

(Continued...)

23 
Table 5. – Continued

Survey 

Extra risk due to fertility pattern (%) 

No 

extra 

risk 

Unavoidable 

firstbirth 

risk 

Single 

risk 

spacing 

<24 

mos. 

Single 

risk 

spacing 

24-35 

mos. 

Single 

risk 

age 

<18 

Single 

risk 

age 

40+ 

Single 

risk 

order 

4+ 

Double 

risk 

spacing 

<24, 

order 

4+ 

Double 

risk 

spacing 

24-35, 

order 

4+ 

Double 

risk 

first 

birth, 

age 

<18 

Double 

risk 

order 

4+, 

age 

40+ 

Double 

risk 

spacing 

<24 

and age 

<18 

Double 

risk 

spacing 

24-35 

and age 

<18 

3-way 

risk 

spacing

<24, 

order 

4+, 

age 

<18 

3-way 

risk 

spacing 

<24, 

order 

4+, 

age 

40+ 

3-way 

risk, 

spacing 

24-35, 

order 

4+, 

age 

40+ Total N 

Liberia 2007 16.4 15.1 6.8 10.2 0.2 0.0 15.4 10.2 12.6 8.4 2.1 0.8 0.5 0.0 0.6 0.7 100.0 14,573 Madagascar 2008–09 13.2 15.1 9.2 11.0 0.2 0.1 12.0 12.8 13.4 8.2 1.4 1.3 0.9 0.0 0.4 0.6 100.0 35,352 Malawi 2010 15.2 15.2 6.7 13.5 0.2 0.0 16.4 7.7 13.1 8.3 1.3 0.7 0.6 0.0 0.3 0.7 100.0 49,927 Mali 2006 8.7 10.3 8.3 11.5 0.3 0.0 12.9 15.1 18.5 9.1 1.1 1.7 1.3 0.1 0.5 0.8 100.0 37,501 Mozambique 2011 15.5 14.6 5.9 13.3 0.3 0.1 14.3 8.1 13.5 9.7 1.6 0.9 0.9 0.1 0.3 0.9 100.0 28,435 Namibia 2006–07 22.7 25.5 5.9 10.6 0.1 0.2 11.7 5.5 8.5 6.5 1.5 0.3 0.2 0.0 0.3 0.4 100.0 12,955 Nepal 2011 18.6 23.4 10.2 13.6 0.1 0.0 9.2 6.5 8.7 7.7 0.6 0.7 0.3 0.0 0.1 0.3 100.0 17,031 Niger 2006 7.9 8.4 7.7 10.8 0.2 0.0 14.2 16.2 19.4 9.2 1.1 2.3 1.3 0.1 0.3 0.7 100.0 26,808 Nigeria 2008 10.3 13.6 8.7 11.8 0.3 0.1 13.3 13.7 15.7 7.0 1.5 1.5 1.0 0.1 0.6 0.9 100.0 70,621 Pakistan 2006–07 8.1 16.1 13.3 10.8 0.1 0.0 11.8 18.7 13.9 3.7 1.0 0.9 0.4 0.1 0.5 0.5 100.0 26,513 Peru 2012 26.6 28.4 6.1 8.4 0.1 0.6 10.9 3.5 6.9 6.2 1.3 0.3 0.2 0.0 0.1 0.3 100.0 25,753 Philippines 2008 14.6 25.8 14.0 10.0 0.0 0.3 10.9 9.6 9.1 2.8 1.3 0.4 0.1 0.0 0.4 0.5 100.0 18,233 Rwanda 2010 11.6 21.3 10.1 13.3 0.0 0.1 13.2 9.2 15.3 1.8 2.4 0.1 0.1 0.0 0.4 1.1 100.0 23,921 Sao Tome and Principe 

2008–09 20.0 19.0 5.8 12.1 0.1 0.2 18.4 5.3 9.1 6.9 2.2 0.3 0.2 0.0 0.1 0.3 100.0 4,652 

Senegal 2010–11 13.1 17.1 7.5 11.9 0.4 0.1 14.0 10.4 14.7 6.6 1.2 1.1 0.8 0.1 0.3 0.6 100.0 28,157 Sierra Leone 2008 15.8 14.8 7.9 11.1 0.5 0.1 13.4 9.6 12.3 9.5 1.1 1.6 1.2 0.1 0.4 0.4 100.0 16,041 Swaziland 2006–07 18.7 19.6 6.2 10.2 0.2 0.0 15.0 7.1 10.4 10.1 0.9 0.4 0.4 0.0 0.2 0.5 100.0 7,300 Tanzania 2010 15.3 15.9 6.5 12.9 0.1 0.0 15.4 7.7 15.9 7.0 1.5 0.4 0.4 0.0 0.3 0.6 100.0 20,454 Timor-Leste 2009 8.6 16.0 11.6 12.3 0.0 0.1 12.6 14.6 17.1 2.3 1.9 0.3 0.1 0.0 0.9 1.4 100.0 26,507 Uganda 2011 9.1 11.4 8.8 11.6 0.3 0.0 13.3 14.8 19.1 7.3 1.2 1.1 0.9 0.0 0.4 0.6 100.0 20,733 Ukraine 2007 26.0 55.9 5.8 5.3 0.0 0.2 1.3 1.0 0.4 3.6 0.1 0.1 0.0 0.0 0.0 0.0 100.0 3,855 Zambia 2007 13.2 14.5 6.6 14.1 0.1 0.0 14.9 8.1 16.5 8.3 1.5 0.8 0.5 0.0 0.2 0.6 100.0 15,484 

(Continued...)

24 
Table 5. – Continued

Survey 

Extra risk due to fertility pattern (%) 

No 

extra 

risk 

Unavoidable 

firstbirth 

risk 

Single 

risk 

spacing 

<24 

mos. 

Single 

risk 

spacing 

24-35 

mos. 

Single 

risk 

age 

<18 

Single 

risk 

age 

40+ 

Single 

risk 

order 

4+ 

Double 

risk 

spacing 

<24, 

order 

4+ 

Double 

risk 

spacing 

24-35, 

order 

4+ 

Double 

risk 

firstbirth, 

age 

<18 

Double 

risk 

order 

4+, 

age 

40+ 

Double 

risk 

spacing 

<24 

and age 

<18 

Double 

risk 

spacing 

24-35 

and age 

<18 

3-way 

risk 

spacing

<24, 

order 

4+, 

age 

<18 

3-way 

risk 

spacing 

<24, 

order 

4+, 

age 

40+ 

3-way 

risk, 

spacing 

24-35, 

order 

4+, 

age 

40+ Total N 

Zimbabwe 2010–11 28.3 25.7 4.3 9.8 0.1 0.1 13.5 2.6 5.8 8.0 1.1 0.3 0.2 0.0 0.1 0.2 100.0 13,405 Total N 15.8 19.3 9.2 11.5 0.2 0.1 12.3 9.4 11.8 6.9 1.1 1.0 0.6 0.0 0.3 0.5 100.0 1,227,161 Note: Percent distributions are based on weighted cases for all individual countries. The total percent distribution, however, is based on unweighted cases, because the 

application of standard individual country weights is not meaningful in the pooled sample and analyses using the pooled data are unweighted. 

25 
26 

Table 6 shows that one in three births has a single extra–risk factor and almost one in three has two risk 

factors, other than being a first birth. Very few births have three risk factors. The countries that have more 

than90 percent of births with additional risk are Jordan, Mali, Niger, Pakistan, Timor–Leste, and Uganda. 

Four countries have more than 60 percent of births with no avoidable risk (no extra risk or are first 

births): Albania, Armenia, Indonesia, and the Ukraine. 

Table 6. Distribution of births 0 to 179 months prior to survey by maternal fertility–related risk 

factors, 45 DHS surveys, 2006–2012 

Survey 

Summary measure of extra risk (%) 

No extra 

risk 

Unavoidable 

firstbirth risk 

Any 

single 

risk 

Any 

double 

risk 

Any 3-

way risk Total N 

Albania 2008–09 31.8 31.7 28.9 7.6 0.0 100.0 6,867 

Armenia 2010 21.8 44.0 30.3 3.7 0.1 100.0 4,167 

Azerbaijan 2006 15.5 36.0 39.6 8.8 0.1 100.0 7,564 

Bangladesh 2011 26.5 17.1 26.0 30.2 0.2 100.0 27,377 

Benin 2006 13.8 15.7 35.3 34.2 1.0 100.0 39,544 

Bolivia 2008 15.3 19.7 32.3 31.8 0.9 100.0 26,730 

Burkina Faso 2010 14.2 14.3 35.8 34.8 0.9 100.0 40,092 

Burundi 2010 11.3 18.4 36.5 32.3 1.6 100.0 18,799 

Cambodia 2010 20.6 26.3 33.2 19.2 0.7 100.0 23,438 

Cameroon 2011 12.3 15.1 33.5 38.2 0.9 100.0 28,932 

Colombia 2010 26.0 28.8 24.6 20.4 0.2 100.0 49,404 

Congo DR 2007 11.5 15.3 33.2 38.3 1.6 100.0 21,330 

Dominican 

Republic 

2007 21.5 23.4 31.2 23.8 0.2 

100.0 

33,076 

Egypt 2008 19.5 27.3 36.8 16.2 0.2 100.0 29,213 

Ethiopia 2011 11.8 13.3 34.4 39.3 1.2 100.0 33,168 

Ghana 2008 21.0 19.7 32.8 25.6 0.9 100.0 7,547 

Guyana 2009 18.9 23.2 33.1 24.4 0.4 100.0 6,025 

India 2005–06 14.7 20.6 34.4 30.1 0.2 100.0 177,993 

Indonesia 2007 29.3 31.0 25.0 14.4 0.4 100.0 48,014 

Jordan 2007 9.1 20.4 44.2 25.8 0.5 100.0 27,230 

Kenya 2008–09 15.2 17.4 34.1 32.2 1.0 100.0 15,448 

Lesotho 2009 24.4 29.4 28.4 17.3 0.4 100.0 9,124 

Liberia 2007 16.4 15.1 32.7 34.6 1.3 100.0 14,573 

Madagascar 2008–09 13.2 15.1 32.6 38.0 1.1 100.0 35,352 

Malawi 2010 15.2 15.2 36.8 31.8 1.0 100.0 49,927 

Mali 2006 8.7 10.3 33.0 46.7 1.3 100.0 37,501 

Mozambique 2011 15.5 14.6 33.9 34.8 1.3 100.0 28,435 

Namibia 2006–07 22.7 25.5 28.5 22.6 0.7 100.0 12,955 

(Continued...)
27 

Table 6. – Continued

Survey 

Summary measure of extra risk (%) 

No extra 

risk 

Unavoidable 

firstbirth risk 

Any 

single 

risk 

Any 

double 

risk 

Any 3-

way risk Total N 

Nepal 2011 18.6 23.4 33.2 24.5 0.4 100.0 17,031 

Niger 2006 7.9 8.4 33.0 49.6 1.1 100.0 26,808 

Nigeria 2008 10.3 13.6 34.2 40.4 1.5 100.0 70,621 

Pakistan 2006–07 8.1 16.1 36.1 38.6 1.1 100.0 26,513 

Peru 2012 26.6 28.4 26.0 18.5 0.5 100.0 25,753 

Philippines 2008 14.6 25.8 35.2 23.5 1.0 100.0 18,233 

Rwanda 2010 11.6 21.3 36.7 28.8 1.5 100.0 23,921 

Sao Tome and 

Principe 

2008–09 20.0 19.0 36.6 23.9 0.5 100.0 4,652 

Senegal 2010–11 13.1 17.1 33.8 34.9 1.0 100.0 28,157 

Sierra Leone 2008 15.8 14.8 33.0 35.5 1.0 100.0 16,041 

Swaziland 2006–07 18.7 19.6 31.6 29.4 0.7 100.0 7,300 

Tanzania 2010 15.3 15.9 35.0 33.0 0.9 100.0 20,454 

Timor-Leste 2009 8.6 16.0 36.6 36.5 2.3 100.0 26,507 

Uganda 2011 9.1 11.4 34.0 44.4 1.2 100.0 20,733 

Ukraine 2007 26.0 55.9 12.7 5.3 0.0 100.0 3,855 

Zambia 2007 13.2 14.5 35.8 35.7 0.9 100.0 15,484 

Zimbabwe 2010–11 28.3 25.7 27.7 18.0 0.3 100.0 13,405 

 

Total N 15.8 19.3 33.3 30.8 0.8 100.0 1,227,161 

Note: Percent distributions are based on weighted cases for all individual countries. The total percent distribution, 

however, is based on unweighted cases, because the application of standard individual country weights is not 

meaningful in the pooled sample and analyses using the pooled data are unweighted. 

Bivariate Results 

Infant and child mortality 

The DHS surveys collect age at death for non–surviving children in three scales. For children who died at 

less than one month, age is collected in days. For non–surviving children dying within two years of birth, 

age at death is collected in number of months. Number of years is used for children who died at an age of 

two or more years. Dates of birth of children are given in calendar year and month. Preceding birth–to–

conception intervals are calculated by the difference between the date of birth of the index child and the 

immediately preceding child and subtracting the duration of gestation. Only singleton births are used for 

the index children. 

Infant and child mortality by spacing interval 

The analysis of infant and child mortality includes the following mortality rates: early neonatal (deaths 

that occur 0–6 days after a live birth), neonatal (deaths within the first 30 days among all children born 
28 

alive), post–neonatal (deaths to children at ages 1–11 months among children surviving the neonatal 

period), infant (deaths to children at ages 0–11 months among all children born alive), child mortality 

(deaths to children at ages one to four years among children who survive to age one year) and under–five 

mortality (deaths to children under five years of age among all children born alive). 

The first panel of Table 7 shows the mortality rates by length of preceding birth–to–conception interval. 

From the pooled data set for the 45 surveys, on average, children conceived after short intervals–under 6 

months between birth and conception and 6–11 months–are respectively 3.8 and 2.6 times as likely to die 

before their fifth birthday, as are children conceived after 36–47 months. Also, those children conceived 

after intervals of 12–17 months, 18–23 months, and 24–29 months have a 112 percent, 69 percent, and 34 

percent, respectively, greater chance of dying, than do children conceived after 36–47 months. These 

results are very similar to those found in the preceding 52–country study. 

Similar patterns of excess mortality by interval durations occur for infant mortality and neonatal 

mortality. Compared with a preceding birth–to–conception interval of 36–47 months, infant mortality is 

higher on average by 246 percent, 122 percent, 71 percent, and 34 percent for intervals of fewer than 6 

months, 6–11 months, 12–17 months, and 18–23 months, respectively. For neonatal mortality the average 

excess mortality is 287 percent, 118 percent, 60 percent, and 26 percent for intervals of fewer than 6 

months, 6–11 months, 12–17 months, and 18–23 months, respectively. The pattern of excess post–

neonatal mortality is similar to that of neonatal mortality for intervals of fewer than 36–47 months but has 

a non–significant declining level for intervals of 48 months or longer. 

Infant and child mortality by mother’s age at birth 

A U–shaped pattern exists for neonatal, post–neonatal, infant, and child mortality with respect to the 

mother’s age at birth (second panel of Table 7). Relative to the risk of dying for births that occurred when 

the mother was 18–24 years of age, births to mothers under 18 years of age had a 41 to 60 percent 

increased risk of mortality at all ages of exposure. The risk of mortality also increased for children born to 

mothers 40 years of age or older–around 30 percent greater mortality risk in the neonatal, post–neonatal, 

and infant age groups, and a 17 percent greater risk for under–five mortality. Being born when the mother 

is between 25 and 34 years of age had a lower risk of dying for all ages under five years. 

Infant and child mortality by birth order 

Being a firstborn child carries a greater risk of mortality than being a second–born child, a 47 percent 

greater risk of dying during the neonatal period, 29 percent during infancy, and 21 percent at all ages 

under five years (third panel of Table 7). For the post–neonatal and child periods, being a firstborn does 

not have a significantly different risk of dying than being second born. However, births of order five or 

higher do incur higher risks of dying during all periods under age five, with the extra risk increasing in the 

post–neonatal and child periods. 
Table 7. Unadjusted relative risk of mortality by duration of preceding birth–to–conception interval, mother’s age at child’s birth, and the 

birth order, children born 0 to 179 months prior to the survey, 45 DHS surveys, 2006–2012 

Early neonatal Neonatal Post-neonatal Infant Child Under five 

uRR CI- CI+ uRR CI- CI+ uRR CI- CI+ uRR CI- CI+ uRR CI- CI+ uRR CI- CI+ 

Birth-to-conception interval (months) <6 3.87 3.42 4.37 3.99 3.58 4.44 2.93 2.61 3.29 3.46 3.20 3.75 2.90 2.73 3.09 3.81 3.67 3.95 6-11 2.18 1.94 2.45 2.28 2.06 2.53 2.16 1.94 2.39 2.22 2.06 2.38 2.31 2.18 2.44 2.55 2.46 2.64 12-17 1.60 1.43 1.78 1.67 1.52 1.84 1.75 1.59 1.93 1.71 1.60 1.83 2.26 2.14 2.38 2.12 2.05 2.19 18-23 1.26 1.12 1.42 1.30 1.17 1.44 1.38 1.25 1.53 1.34 1.25 1.44 1.87 1.77 1.98 1.69 1.63 1.75 24-29 1.02 0.90 1.16 1.08 0.97 1.20 1.18 1.06 1.32 1.13 1.05 1.22 1.48 1.39 1.57 1.34 1.29 1.39 30-35 1.08 0.94 1.24 1.13 1.00 1.27 1.03 0.92 1.17 1.08 0.99 1.18 1.28 1.19 1.37 1.16 1.12 1.22 36-47 (ref.) 1.00 1.00 1.00 1.00 1.00 1.00 48-59 1.08 0.93 1.26 1.04 0.91 1.19 0.98 0.86 1.13 1.01 0.92 1.12 0.77 0.71 0.84 0.87 0.83 0.92 60-95 1.20 1.04 1.38 1.18 1.04 1.33 0.89 0.78 1.01 1.03 0.94 1.13 0.63 0.57 0.68 0.83 0.79 0.87 96+ 1.56 1.31 1.85 1.44 1.24 1.68 0.83 0.69 1.00 1.14 1.01 1.28 0.53 0.46 0.61 0.87 0.81 0.93 First births 2.04 1.85 2.26 1.98 1.81 2.16 1.21 1.10 1.32 1.59 1.50 1.70 1.27 1.21 1.34 1.72 1.67 1.77 Total N 424,907 424,907 424,907 424,907 1,176,384 1,176,384 Mother’s age at child’s birth<18 1.59 1.48 1.71 1.57 1.47 1.67 1.41 1.31 1.52 1.50 1.43 1.57 1.46 1.41 1.51 1.60 1.57 1.63 18-24 (ref.) 1.00 1.00 1.00 1.00 1.00 1.00 25-34 0.79 0.75 0.83 0.79 0.76 0.83 0.95 0.90 0.99 0.86 0.83 0.89 0.97 0.95 1.00 0.91 0.89 0.92 35-39 1.02 0.94 1.10 1.01 0.94 1.08 1.08 1.00 1.16 1.04 0.99 1.10 1.05 1.01 1.10 1.04 1.02 1.07 40+ 1.31 1.18 1.46 1.28 1.17 1.40 1.32 1.19 1.46 1.30 1.21 1.39 1.16 1.07 1.25 1.17 1.12 1.22 Total N 424,948 424,948 424,948 424,948 1,176,388 1,176,388 Birth order 1 1.55 1.45 1.65 1.47 1.39 1.55 1.07 1.00 1.14 1.29 1.24 1.34 0.97 0.94 1.00 1.21 1.19 1.23 2 (ref.) 1.00 1.00 1.00 1.00 1.00 1.00 3-4 0.97 0.90 1.03 0.96 0.91 1.02 1.15 1.08 1.23 1.05 1.01 1.10 1.20 1.16 1.24 1.11 1.09 1.14 5-6 1.14 1.06 1.24 1.16 1.08 1.24 1.40 1.31 1.51 1.27 1.21 1.33 1.50 1.45 1.56 1.36 1.33 1.39 7+ 1.43 1.32 1.55 1.45 1.36 1.56 1.70 1.58 1.83 1.56 1.49 1.65 1.92 1.85 2.00 1.71 1.67 1.75 Total N 424,948 424,948 424,948 424,948 1,176,388 1,176,388 Note: Age range of analysis: ENN (early neonatal), NN (neonatal), PNN (post–neonatal), and Infant Mortality: births in 0–59 months prior to survey. Child and Under–Five Mortality: births in 0–179 months prior to survey. 

29 
30 

Infant and child mortality by multiple fertility extra risk factors 

As seen in Tables 5 and 6, a child may be subject to one extra risk factor or two or three factors 

simultaneously. Tables 8 and 9 show their combined effects on infant and child mortality in full 

combinations and by number of risk factors, respectively. Beyond no extra risk and the unavoidable risk 

of first birth, Table 8 lists 19 combinations of extra risk. As shown in Table 5, some combinations are rare 

while others are frequent. Fifteen of the combinations have significant relationships with under–five 

mortality, all of which increase the risk of dying under age five. 

The greatest increases have relative risks of more than six and four times that of children not in any extra–

risk category and are made up of children with spacing intervals of fewer than 24 months, birth order four 

or higher, and ages at birth of less than 18 years or 40 years or more, respectively. However, very few 

births occur with these combinations of risk factors. Among those with 1 percent or more of the births, 

single risks of spacing fewer than 24 months, spacing 24–35 months, and maternal age 40 years or more 

carry extra risks of 25 to 133 percent. For double risks, children born with the combinations of birth order 

four or higher with spacing of fewer than 24 months or maternal age 40 years or more carry extra risks of 

dying under age five years of 255 percent and 53 percent greater than those born with no extra risk. 

Similarly, children born to mothers under age 18 and who are either first births or with a spacing of fewer 

than 24 months have increased risks of dying under age five years of 184 percent and 303 percent, 

respectively. 

Table 9 demonstrates that the risk of dying under five years of age relative to that of children with no 

extra fertility risk factor increases with the number of factors from 55 percent extra risk for first births 

alone to 67 percent for one avoidable risk factor, 174 percent for two risk factors, and 227 percent for 

three risk factors. For all age at death intervals and all categories, the increased risk of dying is 

significant. 
Table 8. Unadjusted relative risk of mortality by the mother’s fertility–related risk, children born 0 to 179 months prior to the survey, 45 

DHS surveys, 2006–2012 

Early neonatal Neonatal Post-neonatal Infant Child Under five 

uRR CI- CI+ uRR CI- CI+ uRR CI- CI+ uRR CI- CI+ uRR CI- CI+ uRR CI- CI+ 

Extra risk due to fertility pattern No extra risk (ref.) 1.00 1.00 1.00 1.00 1.00 1.00 Unavoidable first-birth risk 1.81 1.68 1.96 1.76 1.64 1.89 1.16 1.07 1.25 1.48 1.40 1.56 1.19 1.14 1.25 1.55 1.51 1.60 Single risk spacing <24 months 1.89 1.72 13.41 1.93 1.78 2.10 1.86 1.69 2.03 1.90 1.78 2.02 2.12 2.02 2.23 2.33 2.27 2.40 Single risk spacing 24-35 months 1.04 0.94 7.41 1.12 1.02 1.22 1.32 1.20 1.44 1.21 1.14 1.29 1.85 1.76 1.94 1.61 1.56 1.66 Single risk age <18 0.84 0.37 5.94 0.87 0.43 1.74 1.19 0.64 2.22 1.02 0.64 1.62 1.86 1.44 2.40 1.46 1.23 1.74 Single risk age 40+ 2.39 1.60 16.95 2.15 1.49 3.11 1.39 0.85 2.27 1.80 1.34 2.41 0.63 0.35 1.14 1.45 1.16 1.81 Single risk order 4+ 1.06 0.96 7.49 1.08 1.00 1.18 1.21 1.11 1.32 1.14 1.07 1.21 1.36 1.30 1.44 1.25 1.21 1.28 Double risk spacing <24, order 4+ 2.49 2.27 17.66 2.69 2.48 2.91 2.95 2.71 3.20 2.81 2.65 2.97 3.60 3.44 3.76 3.55 3.46 3.65 Double risk spacing 24-35, order 4+ 1.30 1.19 9.26 1.37 1.26 1.48 1.76 1.62 1.91 1.55 1.46 1.64 2.52 2.41 2.64 2.10 2.04 2.16 Double risk first birth, age <18 2.52 2.29 17.91 2.52 2.31 2.74 1.98 1.80 2.18 2.27 2.13 2.42 2.38 2.26 2.50 2.84 2.76 2.92 Double risk first birth, age 40+ 1.29 0.42 9.18 1.00 0.32 3.12 1.12 0.36 3.49 1.06 0.48 2.36 nc nc nc 0.87 0.48 1.56 Double risk order 4+, age <18 40.53 5.73 287.74 31.30 4.41 222.20 nc nc nc 20.82 2.93 147.67 nc nc nc 3.90 0.55 27.68 Double risk order 4+, age 40+ 1.65 1.40 11.71 1.61 1.39 1.85 1.44 1.23 1.70 1.53 1.38 1.70 1.46 1.28 1.66 1.53 1.42 1.65 Double risk spacing <24 and age <18 

3.30 2.68 23.41 3.27 2.72 3.94 2.90 2.35 3.57 3.10 2.70 3.56 3.78 3.46 4.12 4.03 3.83 4.24 

Double risk spacing 24-35 and age <18 

1.67 1.20 11.86 1.87 1.42 2.47 2.06 1.56 2.73 1.96 1.61 2.39 3.52 3.16 3.91 2.78 2.59 2.99 

Double risk spacing <24 and age 40+ 

1.17 0.16 8.29 0.91 0.13 6.44 3.06 0.98 9.50 1.92 0.72 5.12 0.99 0.25 3.96 2.02 1.15 3.56 

Double risk spacing 24-35 and age 40+ 

2.60 0.84 18.46 2.02 0.65 6.26 nc nc nc 1.08 0.35 3.35 1.09 0.35 3.38 1.25 0.67 2.32 

3-way risk spacing<24, order 4+, age<18 

8.96 3.72 63.58 6.95 2.89 16.73 3.35 0.84 13.42 5.31 2.53 11.16 6.66 4.65 9.54 6.14 4.92 7.67 

3-way risk spacing <24, order 4+, age 40+ 

3.66 2.90 25.99 3.73 3.04 4.57 4.03 3.26 4.99 3.87 3.34 4.48 4.05 3.48 4.71 4.16 3.82 4.54 

3-way risk spacing 24-35, order 4+, age<18 

0.01 0.00 0.05 4.47 0.63 31.74 nc nc nc 2.34 0.33 16.60 2.87 0.93 8.92 1.80 0.75 4.32 

3-way risk, spacing 24-35, order 4+, age 40+ 

2.31 1.89 16.43 2.41 2.02 2.87 2.25 1.85 2.74 2.33 2.05 2.66 2.73 2.38 3.14 2.63 2.43 2.85 

Total N 424,907 424,907 424,907 424,907 1,176,388 1,176,388 Note: Age range of analysis: ENN, NN, PNN, and Infant Mortality: 0-59 months Child and Under-Five Mortality: 0-179 months 

31 
Table 9. Unadjusted relative risk of mortality by the mother’s fertility-related risk, children born 0 to 179 months prior to the survey, 45 

DHS surveys, 2006–2012 

Early neonatal Neonatal Post-neonatal Infant Child Under five 

aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ 

Extra risk due to fertility pattern No extra risk (ref.) 1.00 1.00 1.00 1.00 1.00 1.00 

Unavoidable first-birth risk 1.81 1.68 1.96 1.76 1.64 1.89 1.16 1.07 1.25 1.48 1.40 1.52 1.19 1.14 1.25 1.55 1.51 1.60 

Any single risk 1.25 1.16 1.35 1.29 1.21 1.38 1.39 1.30 1.50 1.34 1.28 1.37 1.75 1.68 1.82 1.67 1.63 1.71 Any double risk 1.93 1.79 2.08 2.00 1.87 2.13 2.10 1.96 2.25 2.05 1.95 2.10 2.82 2.71 2.94 2.74 2.68 2.81 Any 3-way risk 2.79 2.38 3.27 2.87 2.50 3.29 2.81 2.42 3.27 2.84 2.57 2.99 3.33 3.01 3.69 3.27 3.08 3.47 

Missing 0.03 0.00 >1000 0.03 0.00 >1000 Total N 424,907 424,907 424,907 424,907 1,176,388 1,176,388 

Note: Age range of analysis: 

ENN, NN, PNN, and Infant Mortality: 0-59 months Child and Under-Five Mortality: 0-179 months 

32 
33 

Nutritional status 

Nutritional status was determined by anthropometric measurements on children under age five at the time 

of the survey except in Indonesia, the Philippines, and Ukraine, where anthropometry was not included. 

Children who were born in the month of interview were not analyzed. Table 10 presents the unadjusted 

odds of children being stunted, underweight, and wasted according to the duration of the preceding birth–

to–conception interval, the mother’s age at birth, and the child’s birth order for the pool of the 45 latest 

DHS surveys. 

Table 10. Unadjusted odds ratios for stunting, underweight, and wasting by duration of preceding 

birth–to–conception interval, mother’s age at child’s birth, and birth order, living children age 0 to 

59 months at survey, 42 DHS surveys, 2006–2012 

 Stunting Underweight Wasting 

 uOR CI- CI+ uOR CI- CI+ uOR CI- CI+ 

Birth-to-conception interval (months) 

<6 1.47 1.39 1.55 1.46 1.38 1.54 1.05 0.95 1.15 

6-11 1.43 1.37 1.49 1.37 1.31 1.43 1.08 1.01 1.16 

12-17 1.44 1.39 1.49 1.39 1.33 1.44 1.13 1.06 1.19 

18-23 1.27 1.23 1.31 1.20 1.16 1.25 1.06 1.00 1.13 

24-29 1.22 1.18 1.26 1.18 1.13 1.22 1.03 0.97 1.10 

30-35 1.09 1.04 1.13 1.05 1.00 1.10 1.04 0.97 1.11 

36-47 (ref.) 1.00 1.00 1.00 

48-59 0.90 0.86 0.94 0.93 0.88 0.98 0.98 0.90 1.06 

60-95 0.75 0.72 0.79 0.76 0.73 0.80 0.89 0.83 0.96 

96+ 0.62 0.58 0.66 0.64 0.59 0.69 0.69 0.61 0.77 

First births 0.89 0.86 0.92 0.90 0.87 0.93 0.89 0.84 0.94 

Total N 348,122 348,122 348,740 

Mother’s age at child’s birth 

<18 1.09 1.06 1.13 1.09 1.05 1.13 0.95 0.89 1.00 

18-24 (ref.) 1.00 1.00 1.00 

25-34 0.95 0.93 0.97 0.93 0.91 0.95 0.97 0.94 1.00 

35-39 0.98 0.95 1.01 0.89 0.87 0.93 0.92 0.87 0.97 

40+ 1.08 1.04 1.13 1.03 0.98 1.08 1.01 0.94 1.09 

Total N 348,151 348,151 348,769 

Birth order 

1 0.88 0.86 0.90 0.88 0.86 0.91 0.91 0.87 0.95 

2 (ref.) 1.00 1.00 1.00 

3-4 1.13 1.10 1.15 1.09 1.06 1.12 1.02 0.98 1.06 

5-6 1.29 1.26 1.33 1.22 1.19 1.26 1.12 1.07 1.17 

7+ 1.38 1.34 1.42 1.30 1.26 1.35 1.17 1.11 1.23 

Total N 348,151 348,151 348,769 

Note: p-values for the three exposure variables are <0.000 for all models with the following exception: in the model 

for stunting, mother’s age at birth (p=.010). 
34 

Nutritional status by spacing interval 

The averages show substantial declines in the odds of being stunted and underweight as the birth–to–

conception interval increases after 18 months. The odds of being wasted are significantly a little higher 

for births with an interval of 6–17 months and significantly lower for 60+ months, compared with births 

with a 36–47–month spacing interval. 

Nutritional status by mother’s age at birth and birth order 

Table 10 shows a U–shaped relationship between mother’s age at birth and the odds of being stunted and 

underweight. The odds of being wasted are lower for births to mothers ages 25–39 years than for births to 

mothers ages 18–24 years, and surprisingly are lower for births to mothers ages less than 18 years. 

However, this latter result is on the cusp of significance. The odds of stunting, underweight, and wasting 

all increase with birth order, as shown in Table 10, although the result for wasting for orders three and 

four is not significantly different from that for births of order two. 

Nutritional status by risk category combinations 

Table 11 shows the odds of children being stunted, underweight, and wasted according to combinations of 

extra risk due to fertility behavior. Compared with children not in any extra–risk category, all risk 

categories with significant relationships have increased odds of being stunted except for the single–risk 

categories of first births with a slightly lowered risk and births to women ages 40 and older with 40 

percent lower odds. The results for underweight are similar to those for stunting, with the exception that 

first births to women 40 and older also are less likely to be underweight. Among the significant results for 

wasting, all combinations of risk categories show increased odds of being wasted relative to children in 

no extra–risk category. 

Table 12 indicates that the odds of being stunted, underweight, and wasted increase as the number of 

fertility extra–risk factors increases. There is an 80 percent increase in the odds of being stunted for 

children with three risk factors, compared with those with no risk factor. All results are significant except 

for first births for wasting which is close to that of children with no risk factors. 
Table 11. Unadjusted odds ratios for stunting, underweight, and wasting by the mother’s fertility–related risk, living children age 0 to 59 

months at survey, 45 DHS surveys, 2006–2012 

Stunting Underweight Wasting 

Any 

malnourished 

uOR CI- CI+ uOR CI- CI+ uOR CI- CI+ uOR CI- CI+ 

Extra risk due to fertility pattern No extra risk (ref.) 1.00 1.00 1.00 1.00 Unavoidable first-birth risk 0.95 0.92 0.98 0.96 0.93 0.99 0.98 0.93 1.03 0.96 0.94 0.98 Single risk spacing <24 months 1.48 1.43 1.53 1.46 1.40 1.52 1.18 1.11 1.25 1.43 1.38 1.48 Single risk spacing 24-35 months 1.35 1.31 1.39 1.32 1.27 1.36 1.11 1.05 1.17 1.31 1.27 1.35 Single risk age <18 1.40 1.14 1.72 1.47 1.19 1.83 1.31 0.94 1.84 1.34 1.11 1.62 

Single risk age 40+ 0.60 0.47 0.76 0.67 0.52 0.87 0.89 0.62 1.27 0.64 0.52 0.79 

Single risk order 4+ 1.24 1.20 1.28 1.22 1.18 1.26 1.15 1.10 1.21 1.23 1.19 1.26 

Double risk spacing <24, order 4+ 1.92 1.86 1.99 1.77 1.71 1.84 1.25 1.17 1.33 1.75 1.69 1.81 Double risk spacing 24-35, order 4+ 1.64 1.59 1.69 1.53 1.48 1.58 1.25 1.19 1.32 1.55 1.51 1.59 Double risk first birth, age <18 1.32 1.28 1.38 1.32 1.27 1.38 1.01 0.94 1.08 1.26 1.21 1.30 Double risk first birth, age 40+ 0.79 0.51 1.24 0.56 0.32 0.99 0.34 0.11 1.07 0.72 0.48 1.08 Double risk order 4+, age <18 nc nc nc nc nc nc nc nc nc nc nc nc Double risk order 4+, age 40+ 1.26 1.19 1.34 1.21 1.13 1.29 1.09 0.99 1.21 1.23 1.17 1.30 Double risk spacing <24 and age <18 1.95 1.77 2.16 2.03 1.83 2.26 1.41 1.19 1.67 1.83 1.66 2.01 Double risk spacing 24-35 and age <18 1.74 1.55 1.95 1.61 1.42 1.83 1.30 1.06 1.59 1.64 1.47 1.83 Double risk spacing <24 and age 40+ 1.83 1.04 3.23 1.90 1.04 3.47 1.96 0.84 4.57 1.72 1.00 2.94 Double risk spacing 24-35 and age 40+ 0.88 0.47 1.63 1.18 0.64 2.21 0.74 0.23 2.34 0.86 0.49 1.49 3-way risk spacing <24, order 4+, age<18 3.77 1.84 7.72 1.77 0.76 4.13 0.57 0.08 4.22 2.94 1.44 6.02 3-way risk spacing <24, order 4+, age 40+ 1.87 1.66 2.12 1.64 1.43 1.89 1.28 1.03 1.59 1.65 1.47 1.86 3-way risk spacing 24-35, order 4+, age<18 1.85 0.48 7.14 1.46 0.31 6.86 nc nc nc 1.26 0.33 4.88 

3-way risk spacing 24-35, order 4+, age 40+ 1.76 1.62 1.91 1.65 1.51 1.81 1.29 1.12 1.49 1.67 1.54 1.80 

Total N 348,122 348,122 348,740 348,115 

35 
Table 12. Unadjusted odds ratios for stunting, underweight, and wasting by the mother’s fertility–related risk, living children age 0 to 59 

months at survey, 45 DHS surveys, 2006–2012 

Stunting Underweight Wasting 

Any 

malnourished 

uOR CI- CI+ uOR CI- CI+ uOR CI- CI+ uOR CI- CI+ 

Extra risk due to fertility pattern No extra risk (ref.) 1.00 1.00 1.00 1.00 Unavoidable first-birth risk 0.95 0.92 0.98 0.96 0.93 0.99 0.98 0.93 1.03 0.96 0.94 0.98 

Any single risk 1.33 1.29 1.36 1.30 1.27 1.34 1.14 1.10 1.19 1.30 1.27 1.32 

Any double risk 1.60 1.56 1.64 1.52 1.48 1.56 1.19 1.14 1.24 1.51 1.47 1.54 

Any 3-way risk 1.80 1.68 1.93 1.65 1.53 1.78 1.28 1.13 1.45 1.67 1.56 1.78 

Total N 348,122 348,122 348,740 348,115 

36 
37 

Multivariate Results 

The first panel of Table 13 presents adjusted risk ratios for early neonatal, neonatal, post–neonatal, child 

(one to four years), and under–five mortality by the length of the preceding birth–to–conception interval 

for the pooled data from the 45 surveys. For early neonatal, neonatal, post–neonatal, and infant mortality 

analyses, children born between 0–59 months prior to each survey interview are considered. Children 

born earlier than 59 months prior to the survey are not used because many of the control variables are not 

available for these children. For the child and under–five mortality analyses, children born up to 179 

months prior to the survey are included. Children born at 180 months prior to the survey or earlier are 

excluded due to truncation of the data file.11

Under–five and child mortality 

In the multivariate analysis of under–five and child mortality, several variables that are available for all 

births that occurred from 0–179 months prior to the survey are used to control for the effects of spurious 

relationships. The demographic controls used were sex of the index child, duration of the pregnancy 

(assumed 9 months for births occurring 60–179 months prior to survey), and whether the preceding child 

died before the conception of the index child. The socioeconomic controls used were type of area of 

residence (urban–rural), mother’s education, the household’s quintile on the DHS Wealth Index, type of 

water supply, type of toilet supply, and possession of a refrigerator. The analyses for under–five and child 

mortality are based on 1,176,384 singleton births that had no imputed preceding birth–to–conception 

interval.12

The relationship between the preceding birth–to–conception interval and under–five mortality is highly 

significant (p < 0.001), and each interval group under 36 months is significantly higher than the reference 

group of 36–47 months as well as the group of 96 or more months. Figure 1 shows the weighted average 

effect of the preceding birth–to–conception interval on under–five mortality. The risk of mortality trends 

downward with each increasing birth–to–conception interval–rapidly until 24–29 months, then more 

slowly with longer intervals, and with a final upturn for intervals of 96 or more months’ duration. 

For child (ages one to four years) mortality, the effect of the duration of the preceding birth–to–

conception interval is almost a constant decline in mortality with an increase in interval length (Table 13 

and Figure 1). The risk ratios for all interval groups are significantly different from the reference group. 

The risk of child death falls from 2.5 times that of the 36–47–month group for conceptions within 6 

months of the preceding birth to 0.8 for conceptions at 60 months or more. There is no upturn in child 

mortality for the open–ended long interval as is noticed for under–five mortality. 

 

11 Because the oldest respondents to the surveys are 49 years of age, information on births is increasingly limited to 

younger women as periods in the past are considered. For example, the data on births 180 months prior to the survey 

pertain to women up to the age of 34 years at the child’s birth. 

12Four births had missing birth interval information. 
Table 13. Adjusted relative risk of mortality by duration of preceding birth–to–conception interval, mother’s age at child’s birth, and the 

birth order, children born 0 to 179 months prior to the survey, 45 DHS surveys, 2006–2012 

Early neonatal Neonatal Post-neonatal Infant Child Under five 

aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ 

Birth-to-conception interval (months) <6 2.25 1.97 2.57 2.29 2.04 2.56 1.97 1.74 2.22 2.15 1.97 2.33 2.53 2.38 2.70 3.24 3.12 3.36 6-11 1.65 1.46 1.87 1.69 1.52 1.88 1.64 1.47 1.83 1.67 1.54 1.80 2.10 1.99 2.23 2.33 2.25 2.42 12-17 1.28 1.15 1.44 1.31 1.19 1.45 1.31 1.19 1.45 1.32 1.23 1.41 1.89 1.79 2.00 1.86 1.80 1.92 18-23 1.09 0.97 1.23 1.10 0.99 1.22 1.10 0.99 1.22 1.11 1.03 1.19 1.60 1.51 1.69 1.52 1.47 1.57 24-29 0.92 0.81 1.04 0.95 0.86 1.07 0.99 0.89 1.10 0.98 0.90 1.05 1.30 1.22 1.38 1.22 1.18 1.27 30-35 1.03 0.90 1.18 1.06 0.94 1.20 0.93 0.82 1.05 1.00 0.91 1.08 1.17 1.09 1.25 1.10 1.05 1.15 36-47 (ref.) 1.00 1.00 1.00 1.00 1.00 1.00 48-59 1.18 1.02 1.38 1.16 1.01 1.32 1.13 0.99 1.30 1.14 1.04 1.26 0.86 0.79 0.94 0.94 0.89 0.99 60-95 1.39 1.21 1.60 1.40 1.24 1.59 1.17 1.02 1.34 1.28 1.17 1.41 0.80 0.73 0.87 0.98 0.93 1.03 96+ 1.77 1.48 2.11 1.72 1.47 2.01 1.25 1.03 1.52 1.50 1.33 1.70 0.81 0.70 0.93 1.13 1.05 1.22 First births 2.22 1.98 2.49 2.16 1.95 2.38 1.47 1.32 1.63 1.83 1.70 1.96 1.49 1.41 1.58 2.01 1.94 2.09 Mother’s age at child’s birth <18 1.19 1.10 1.28 1.18 1.10 1.26 1.23 1.14 1.33 1.20 1.14 1.26 1.33 1.28 1.38 1.35 1.32 1.38 18-24 (ref.) 1.00 1.00 1.00 1.00 1.00 1.00 25-34 1.03 0.97 1.10 1.01 0.96 1.07 1.00 0.95 1.07 1.01 0.97 1.05 0.91 0.88 0.94 0.96 0.94 0.97 35-39 1.38 1.24 1.53 1.31 1.20 1.44 1.10 0.99 1.21 1.20 1.12 1.29 0.81 0.77 0.86 0.98 0.95 1.02 40+ 1.85 1.62 2.12 1.71 1.52 1.92 1.31 1.15 1.49 1.51 1.38 1.64 0.80 0.74 0.88 1.03 0.98 1.09 Birth order 1-2 (ref.) 1.00 1.00 1.00 1.00 1.00 1.00 3-4 0.95 0.88 1.02 0.95 0.89 1.01 1.07 1.00 1.14 1.01 0.96 1.05 1.10 1.07 1.14 1.07 1.04 1.09 5-6 1.00 0.91 1.10 1.01 0.93 1.10 1.13 1.04 1.22 1.07 1.01 1.13 1.22 1.17 1.28 1.15 1.12 1.18 7+ 1.00 0.90 1.12 1.03 0.94 1.13 1.20 1.08 1.32 1.11 1.04 1.19 1.44 1.37 1.51 1.28 1.24 1.32 Total N 424,907 424,907 424,907 424,907 1,176,384 1,176,384 

(Continued...)

38 
39 

Table 13. – Continued

Note: In addition to the three key fertility risk behavior characteristics, adjusted models included the following variables: 

ENN, NN, PNN, and Infant Mortality: Sex of index child, urban–rural area of residence, wantedness of child, mother’s education, 

whether conception was a result of contraceptive failure, outcome of preceding pregnancy (live birth or stillbirth), type of provider 

of prenatal care, type of provider of delivery assistance, number of prenatal tetanus injections, timing of first prenatal care visit, 

quintile of DHS Wealth Index, type of water supply, type of toilet facility, possession of refrigerator, duration of pregnancy, and 

whether preceding child died before conception of index child. 

Child and Under–Five Mortality: Sex of index child, urban–rural area of residence, mother’s education, quintile of Wealth Index, 

type of water supply, type of toilet facility, possession of refrigerator, duration of pregnancy, and whether preceding child died 

before conception of index child. 

Age range of analysis: 

ENN, NN, PNN, and Infant Mortality: 0–59 months 

Child and Under–Five Mortality: 0–179 months 

Figure 1. Adjusted relative risks of under–five and child (one to four years) mortality by length of 

birth–to–conception interval, 45 DHS surveys between 2006 and 2012 

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

<6 6-11 12-17 18-23 24-29 30-35 36-47

reference

48-59 60-95 96+

Adjusted relative risk

Interval in months

Under-five mortality

Child (1-4) mortality

Based on 1,176,384 births 0-179 months prior to surveys
40 

Infant and post–neonatal mortality 

The analysis of infant mortality is based on births that occurred 0–59 months prior to the survey to ensure 

full use of available data and control variables. In addition to the control variables included in the analysis 

of under–five years and child mortality, the wantedness of the birth (wanted at the time of conception, 

wanted later, and did not want any more children) is used, together with type of provider of and timing of 

prenatal care, number of prenatal tetanus toxoid injections, and type of provider of delivery assistance. 

Also included in the surveys with reproductive calendar data is whether the birth was the result of a 

contraceptive failure and the outcome of the preceding pregnancy (live birth or stillbirth). The analyses 

for infant, post–neonatal, neonatal, and early neonatal mortality are based on 424,907 singleton births 

with no imputed preceding birth–to–conception interval. 

Compared with a preceding birth–to–conception interval of 36–47 months, children conceived with 

interval durations of fewer than 24 months have significantly higher risks of mortality. There is little 

difference in mortality risk for the duration groups between 24–47 months. However, the mortality risk 

increases for births with durations of 48 months or more. The shorter the duration of the interval for 

intervals of fewer than 24 months, the higher the risk of dying during infancy. Indeed, while children 

conceived 18–23 months after a birth have an 11 percent higher risk, those conceived within 6 months of 

a prior birth have a 115 percent higher risk. The 45–country pooled data set indicates that children 

conceived 24–47 months after a prior birth have the lowest risk of dying in infancy (Figure 2). 

Figure 2. Adjusted relative risks of infant and post–neonatal mortality by length of birth–to–

conception interval, 45 DHS surveys between 2006 and 2012 

0.00

0.50

1.00

1.50

2.00

2.50

<6 6-11 12-17 18-23 24-29 30-35 36-47

reference

48-59 60-95 96+

Adjusted relative risk

Interval in months

Infant mortality

Post-neonatal mortality

Based on 424,907 births 0-59 months prior to surveys
41 

Neonatal and early neonatal mortality 

Table 13 also shows the results for neonatal mortality. The risk of mortality by preceding birth–to–

conception interval is U–shaped with the lowest points at 24–47 months, including the reference group 

(36–47 months). All interval groups outside the period 24–47 months have adjusted relative risks that are 

significantly higher than those of the reference group. Intervals shorter than 24 months have adjusted 

relative risks that are from 10 percent to 129 percent higher than the risk of mortality of the reference 

group. Intervals longer than the reference group have risks that are from 16 percent to 72 percent higher. 

Figure 3 shows the curve of the adjusted relative risks. 

Figure 3 also shows that the curve for early neonatal mortality is quite similar to that for neonatal 

mortality, but the confidence intervals are a little wider because of the smaller number of deaths during 

this shorter age range. 

Figure 3. Adjusted relative risks of neonatal and early neonatal mortality by length of birth–to–

conception interval, 45 DHS surveys between 2006 and 2012 

0.00

0.50

1.00

1.50

2.00

2.50

3.00

<6 6-11 12-17 18-23 24-29 30-35 36-47

reference

48-59 60-95 96+

Adjusted relative risk

Interval in months

Neonatal mortality

Early neonatal mortality

Based on 424,907 births 0-59 months prior to surveys
42 

Mother’s age at birth and infant and child mortality 

Compared with births to mothers aged 18–24 years, those born to mothers under age 18 years have 

significantly higher risks of dying in all the mortality age groups after taking account of a number of 

confounding factors (second panel of Table 13). The excess risk varies from 18 percent in the neonatal 

period to 35 percent for all ages under five years. Children born to mothers ages 25–34 years do not have 

significantly higher risks of dying during infancy but have about a 9 percent lower risk of dying during 

ages one to four years. Children born to mothers 35 years of age or over are significantly more likely to 

die than children in the reference group in the neonatal period but are significantly less likely to die when 

they are one to four years. The change from more to less risk as the child ages causes the risk of under–

five mortality to be not significantly different from the reference group for children of mothers 35 years 

or over. Figure 4 shows the change in this pattern. 

Figure 4. Adjusted relative risks of neonatal and under–five mortality by mother’s age at birth, 45 

DHS surveys between 2006 and 2012 

1.19

1.00

1.03

1.38

1.85

1.35

1.00 0.96 0.98

1.03

0.00

0.50

1.00

1.50

2.00

2.50

< 18 18 to 24 25 to 34 35 to 39 40+

Adjusted relative risk

Age in Years

Neonatal Mortality

Under-five mortality

Based on 1,176,384 births 0-179 months prior to surveys

18 to 24 

reference
43 

Birth order and infant and child mortality 

Birth order of the child is not significantly related to the risk of dying in the neonatal period after taking 

account of confounding factors (third panel of Table 13). However, for children ages 1–59 months, 

children with birth orders three or higher have greater risks of dying than do first– and second–born 

children, the reference group (the increased risk for third– and fourth–born children in the post–neonatal 

period is almost significant). For all under–five mortality, the higher the birth order, the higher the 

mortality risk (Figure 5). 

Figure 5. Adjusted relative risks of under–five mortality by birth order, 45, DHS surveys between 

2006 and 2012 

Combined risk categories and infant and child mortality 

Children can have more than one fertility behavior risk factor at the same time. Table 14 shows the 

adjusted relative risk of dying at various age intervals according to single risk factors and combinations of 

risk factors, adjusted for confounding characteristics. For under–five mortality compared with children 

with no extra risk factor, 14 combinations of risk factors have relative risks that are significantly different 

from the reference category (Figure 6). They vary from a high of 251 percent extra risk for the 

combination of spacing of fewer than 24 months, birth order four or higher, and maternal age at birth of 

1.00

1.07

1.15

1.28

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

 1-2 3-4 5-6 7+

Adjusted relative risk

Birth order

Based on 1,176,384 births 0-179 months prior to surveys

1-2 

reference
44 

less than 18 years (a very rare category) to 15 percent greater risk for fourth or higher order births to 

women age 40 years or over. During infancy, two of the combinations do not show significantly higher 

risks of mortality, compared with no extra risk: children born with a spacing of fewer than 24 months to 

women ages 40 years or over and children born with a spacing of 24–35 months to women under 18 years 

of age. During ages one to four years, the combination of a birth order of four or higher to women ages 40 

years or over is not significant. 
45 

Table 14. Adjusted relative risk of mortality by the mother’s fertility–related risk, children born 0 to 179 months prior to the survey, 45 

DHS surveys, 2006–2012 

Early neonatal Neonatal 

Postneonatal Infant Child Under five 

aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+

Extra risk due to fertility pattern No extra risk (ref.) 1.00 1.00 1.00 1.00 1.00 1.00

Unavoidable first-birth risk 1.83 1.69 1.99 1.80 1.68 1.94 1.24 1.14 1.35 1.54 1.46 1.63 1.35 1.29 1.42 1.77 1.72 1.81

Single risk spacing <24 months 1.34 1.21 9.51 1.34 1.23 1.47 1.33 1.21 1.46 1.34 1.26 1.43 1.92 1.82 2.01 2.08 2.02 2.14Single risk spacing 24-35 months 0.84 0.76 6.00 0.89 0.81 0.97 0.97 0.88 1.06 0.93 0.87 0.99 1.53 1.45 1.60 1.38 1.34 1.43Single risk age <18 0.60 0.27 4.28 0.60 0.30 1.21 0.69 0.37 1.29 0.66 0.41 1.04 1.19 0.92 1.54 1.02 0.86 1.21Single risk age 40+ 3.05 2.05 21.68 2.79 1.93 4.04 2.04 1.24 3.34 2.47 1.83 3.31 0.78 0.43 1.41 1.71 1.37 2.14Single risk order 4+ 0.95 0.86 6.75 0.96 0.88 1.04 0.96 0.88 1.05 0.96 0.91 1.02 1.00 0.95 1.06 0.99 0.96 1.02Double risk spacing <24, order 4+ 1.53 1.38 10.85 1.59 1.46 1.73 1.64 1.50 1.79 1.62 1.53 1.73 2.40 2.29 2.51 2.54 2.47 2.61Double risk spacing 24-35, order 4+ 0.99 0.90 7.06 1.01 0.92 1.10 1.11 1.02 1.21 1.07 1.00 1.13 1.68 1.60 1.76 1.55 1.51 1.59Double risk first birth, age <18 2.18 1.98 15.49 2.16 1.98 2.35 1.61 1.46 1.77 1.90 1.78 2.02 1.88 1.79 1.98 2.51 2.43 2.58Double risk first birth, age 40+ 1.75 0.56 12.45 1.37 0.44 4.26 1.89 0.61 5.87 1.56 0.70 3.47 0.01 0.00 >1000 1.23 0.68 2.22Double risk order 4+, age <18 21.93 3.02 155.72 14.63 2.03 105.67 nc nc nc 10.04 1.41 71.74 nc nc nc 2.05 0.29 14.52Double risk order 4+, age 40+ 1.65 1.40 11.74 1.58 1.36 1.83 1.26 1.07 1.49 1.43 1.28 1.59 0.99 0.87 1.13 1.15 1.07 1.24Double risk spacing <24 and age <18 1.72 1.39 12.25 1.66 1.37 2.00 1.52 1.23 1.88 1.61 1.40 1.85 2.46 2.25 2.68 2.72 2.58 2.86Double risk spacing 24-35 and age <18 1.05 0.75 7.47 1.14 0.86 1.51 1.13 0.85 1.49 1.14 0.93 1.39 2.15 1.93 2.39 1.88 1.75 2.01Double risk spacing <24 and age 40+ 0.86 0.12 6.11 0.66 0.09 4.70 2.43 0.78 7.54 1.46 0.55 3.90 0.92 0.23 3.70 1.91 1.08 3.36Double risk spacing 24-35 and age 40+ 2.53 0.81 17.97 1.94 0.63 6.03 nc nc nc 1.05 0.34 3.25 0.99 0.32 3.06 1.19 0.64 2.213-way risk spacing <24, order 4+, age<18 3.81 1.58 27.04 2.85 1.18 6.88 1.43 0.36 5.74 2.28 1.09 4.79 3.41 2.38 4.89 3.51 2.81 4.383-way risk spacing <24, order 4+, age 40+ 2.41 1.90 17.13 2.35 1.91 2.89 2.29 1.84 2.84 2.33 2.00 2.70 2.37 2.04 2.76 2.69 2.47 2.933-way risk spacing 24-35, order 4+, age <18 0.00 0.00 0.01 2.34 0.33 16.66 nc nc nc 1.10 0.15 7.81 1.37 0.44 4.24 0.98 0.41 2.363-way risk spacing 24-35, order 4+, age 40+ 1.88 1.53 13.31 1.88 1.57 2.25 1.52 1.25 1.86 1.71 1.50 1.96 1.64 1.43 1.88 1.79 1.65 1.94Total N 424,907 424,907 424,907 424,907 1,176,388 1,176,388 Note: Adjusted models included the following variables: 

ENN, NN, PNN, and Infant Mortality: Sex of index child, urban–rural area of residence, wantedness of child, mother’s education, whether conception was a result of contraceptive failure, outcome of preceding pregnancy (live birth or stillbirth), type of provider of prenatal care, type of provider of delivery assistance, number of prenatal tetanus injections, timing of first prenatal care visit, quintile of DHS Wealth Index, type of water supply, type of toilet facility, possession of refrigerator, duration of pregnancy, and whether preceding child died before conception of index child. 

(Continued...)

45 
46 

Table 14. – Continued

Child and Under–Five Mortality: Sex of index child, urban–rural area of residence, mother’s education, quintile of Wealth Index, 

type of water supply, type of toilet facility, possession of refrigerator, duration of pregnancy, and whether preceding child died 

before conception of index child. 

Age range of analysis: 

ENN, NN, PNN, and Infant Mortality: 0–59 months 

Child and Under–Five Mortality: 0–179 months 

nc: no cases stunted, underweight, or wasted 

Figure 6. Adjusted relative risk of under–five mortality by combinations of extra–risk fertility 

behavior 

3.51

2.72 2.69

2.54 2.51

2.08

1.91 1.88 1.79 1.77 1.71

1.55

1.38

1.15

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

Adjusted relative risk
47 

Table 15 shows the effects of the number of risk factors on infant and child mortality after controlling for 

the effects of confounders. For under–five, child, and infant mortality, the greater the number of 

behavioral risk factors, the higher the level of risk. First births alone also have higher risks at all ages. 

However, children with only one risk factor do not have significantly higher risks of dying during the 

early neonatal, neonatal, and post–neonatal periods when taken separately. They do have significantly 

higher mortality, however, when taken over infancy as a whole. 

Table 15. Adjusted relative risk of mortality by the mother’s fertility–related risk, children born 0 to 

179 months prior to the survey, 45 DHS surveys, 2006–2012 

 

Early 

neonatal Neonatal 

Postneonatal Infant Child Under five 

 aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+ aRR CI- CI+

Extra risk due to 

fertility pattern

No extra 

risk (ref.) 

1.00 1.00 1.00 1.00 1.00 1.00

Unavoidable 

first-birth risk 

1.79 1.65 1.94 1.76 1.64 1.89 1.24 1.14 1.34 1.53 1.45 1.57 1.36 1.29 1.42 1.77 1.72 1.81

Any single 

risk 

1.05 0.97 1.13 1.06 0.99 1.13 1.05 0.97 1.12 1.06 1.01 1.08 1.41 1.35 1.47 1.41 1.38 1.45

Any double 

risk 

1.47 1.36 1.59 1.47 1.38 1.58 1.36 1.27 1.46 1.43 1.36 1.46 1.95 1.88 2.03 2.09 2.04 2.14

Any 3-way 

risk 

2.20 1.87 2.59 2.16 1.88 2.49 1.79 1.53 2.08 1.99 1.79 2.09 1.97 1.78 2.18 2.19 2.06 2.32

Total N 424,907 424,907 424,907 424,907 1,176,388 1,176,388 

Note: Adjusted models included the following variables: 

ENN, NN, PNN, and Infant Mortality: Sex of index child, urban–rural area of residence, wantedness of child, mother’s education,

whether conception was a result of contraceptive failure, outcome of preceding pregnancy (live birth or stillbirth), type of provider of 

prenatal care, type of provider of delivery assistance, number of prenatal tetanus injections, timing of first prenatal care visit, quintile 

of DHS Wealth Index, type of water supply, type of toilet facility, possession of refrigerator, duration of pregnancy, and whether 

preceding child died before conception of index child. 

Child and Under–Five Mortality: Sex of index child, urban–rural area of residence, mother’s education, quintile of Wealth Index, type 

of water supply, type of toilet facility, possession of refrigerator, duration of pregnancy, and whether preceding child died before 

conception of index child. 

Age range of analysis: 

ENN, NN, PNN, and Infant Mortality: 0–59 months 

Child and Under–Five Mortality: 0–179 months 

Nutritional status 

Logistic regressions examined the effects of the duration of preceding birth to conception, mother’s age at 

birth, and birth order on the percentage of children stunted, underweight, and wasted at the time of the 

surveys. To control for potentially confounding factors, the following variables were included in the 

regressions: child’s age, sex, gestation length, education, area of residence, prenatal care provider, timing 

of first prenatal care visit, number of prenatal tetanus toxoid vaccinations, formation of the birth 

attendant, wantedness of the pregnancy, source of drinking water, type of toilet facility in the household, 

an index of household wealth, and whether the household has a refrigerator. All three independent 

variables of interest were also included in the logistic regressions. Table 16 shows the results of the 

analyses. 
48 

Table 16. Adjusted odds ratios for stunting, underweight, and wasting by duration of preceding 

birth–to–conception interval, mother’s age at child’s birth, and birth order, living children age 0 to 

59 months at survey, 45 DHS surveys, 2006–2012 

 Stunting Underweight Wasting 

 aOR CI- CI+ aOR CI- CI+ aOR CI- CI+ 

Birth-to-conception interval 

(months) 

<6 1.39 1.31 1.47 1.38 1.29 1.47 1.01 0.91 1.11 

6-11 1.35 1.29 1.41 1.29 1.23 1.36 1.06 0.98 1.14 

12-17 1.27 1.23 1.32 1.23 1.18 1.28 1.06 0.99 1.12 

18-23 1.15 1.11 1.19 1.10 1.06 1.15 1.01 0.95 1.07 

24-29 1.13 1.09 1.17 1.09 1.05 1.14 0.97 0.91 1.04 

30-35 1.03 0.99 1.08 0.99 0.95 1.04 1.00 0.93 1.07 

36-47 (ref.) 1.00 1.00 1.00 

48-59 0.96 0.92 1.01 1.00 0.95 1.06 1.02 0.94 1.10 

60-95 0.92 0.88 0.97 0.96 0.91 1.01 1.04 0.96 1.13 

96+ 0.86 0.80 0.93 0.96 0.89 1.04 0.93 0.82 1.05 

First births 1.04 1.01 1.09 1.06 1.01 1.10 1.01 0.95 1.08 

Mother’s age at child’s birth 

<18 1.08 1.04 1.11 1.09 1.05 1.13 0.98 0.93 1.05 

18-24 (ref.) 1.00 1.00 1.00 

25-34 0.95 0.93 0.98 0.96 0.93 0.98 1.00 0.96 1.04 

35-39 0.92 0.89 0.96 0.89 0.85 0.93 0.95 0.88 1.01 

40+ 0.95 0.90 1.00 0.95 0.89 1.01 1.00 0.91 1.10 

Birth order 

1-2 (ref.) 1.00 1.00 1.00 

3-4 1.03 1.01 1.06 1.01 0.98 1.03 0.97 0.93 1.02 

5-6 1.08 1.04 1.11 1.04 1.00 1.08 1.01 0.95 1.06 

7+ 1.07 1.03 1.12 1.05 1.00 1.10 1.01 0.94 1.08 

Total N 348,122 348,122 348,740 

Note: In addition to the three key fertility risk behavior characteristics, adjusted models included the following 

variables: 

Sex of index child, urban–rural area of residence, wantedness of child, mother’s education, whether conception 

was a result of contraceptive failure, outcome of preceding pregnancy (live birth or stillbirth), type of provider of 

prenatal care, type of provider of delivery assistance, number of prenatal tetanus injections, timing of first prenatal 

care visit, quintile of DHS Wealth Index, type of water supply, type of toilet facility, possession of refrigerator, 

duration of pregnancy, and whether preceding child died before conception of index child. 

Note that in the model predicting underweight, birth order was not a significant variable (p=.053). In the model 

predicting wasting, preceding birth to pregnancy interval (p=0.20), mother’s age at child’s birth (0.38), and birth 

order (0.40) were not significant. 
49 

Forty–two of the country surveys collected information on height and weight of children. The sample size 

from the pooled data set for nutritional status is 348,122. Note that these are the cases available for 

analysis after removing those with missing or erroneous data for any of the nutritional status variables. 

The total number of cases for multivariate analysis is a little lower than that for the unadjusted analysis 

due to missing data on some of the independent variables. 

Figure 7 shows the adjusted odds ratios for birth–to–conception interval from the multivariate logistic 

regression analyses for stunting and underweight. Wasting is not shown as none of the results is 

significantly different from the reference category (Table 16, first panel). It is clear that chronic and 

overall undernutrition declines substantially with longer intervals. Indeed, children conceived after an 

interval of 12–17 months are 27 percent more likely to be stunted and 23 percent more likely to be 

underweight than children conceived after an interval of 36–47 months. Children conceived after even 

longer durations are less likely to be stunted than are children conceived during the reference period. The 

odds of a child being wasted (acute malnutrition) do not follow the pattern of chronic and overall 

undernutrition as the spacing interval is not significantly related once confounding factors have been 

taken into account. 

Figure 7. Adjusted relative odds of stunting and underweight by birth–to–conception interval, 42 

DHS surveys between 2006 and 2012 

0.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1.40

1.50

1.60

<6 6-11 12-17 18-23 24-29 30-35 36-47

reference

48-59 60-95 96+

Adjusted relative odds

Months

Stunting

Underweight

Based on 348,122 living children of age 0-59 months
50 

Mother’s age at birth and birth order are significantly related to stunting (second and third panels of Table 

16). Although mother’s age at birth is significantly related to underweight, birth order is not, and neither 

characteristic is related to wasting. Children whose mothers were older (through age 39) at their birth are 

less likely to be stunted and underweight. For children born to mothers of ages 40 years or over, there is 

no significant difference in the odds ratios with children born to mothers age 18–24 years. Increases in 

birth order increase the odds of being stunted but not underweight or wasted. The effects of both mother’s 

age at birth and birth order are not large, being at most 8 percent different from those of the reference 

category. In contrast, children born with a birth–to–conception interval of fewer than 6 months are 39 

percent more likely to be stunted than children of the reference, and children conceived 96 or more 

months after the preceding birth are 14 percent less likely to be stunted. 

Table 17. Adjusted odds ratios for stunting, underweight, and wasting, by the mother’s fertility–

related risk, living children age 0 to 59 months at survey, 45 DHS surveys, 2006–2012 

 Stunting Underweight Wasting 

 aOR CI- CI+ aOR CI- CI+ aOR CI- CI+ 

Extra risk due to fertility pattern 

No extra risk (ref.) 1.00 1.00 1.00 

Unavoidable first-birth risk 1.00 0.97 1.03 1.05 1.01 1.08 1.12 1.06 1.17 

Single risk spacing <24 months 1.45 1.39 1.50 1.40 1.34 1.46 1.04 0.98 1.11 

Single risk spacing 24-35 months 1.20 1.16 1.24 1.17 1.13 1.21 0.97 0.92 1.03 

Single risk age <18 1.05 0.85 1.29 1.12 0.90 1.41 1.12 0.80 1.58 

Single risk age 40+ 0.77 0.61 0.99 0.94 0.72 1.22 1.12 0.78 1.61 

Single risk order 4+ 1.00 0.97 1.03 0.99 0.96 1.03 1.01 0.96 1.07 

Double risk spacing <24, order 4+ 1.50 1.44 1.56 1.37 1.32 1.43 0.98 0.92 1.05 

Double risk spacing 24-35, order 4+ 1.25 1.21 1.29 1.17 1.13 1.22 1.01 0.95 1.06 

Double risk first birth, age <18 1.11 1.07 1.16 1.18 1.13 1.23 1.07 0.99 1.14 

Double risk first birth, age 40+ 1.11 0.70 1.76 0.81 0.45 1.45 0.43 0.14 1.35 

Double risk order 4+, age <18 nc nc nc nc nc nc nc nc nc 

Double risk order 4+, age 40+ 1.02 0.96 1.09 1.02 0.95 1.10 1.00 0.90 1.11 

Double risk spacing <24 and age <18 1.53 1.38 1.70 1.61 1.44 1.80 1.13 0.95 1.35 

Double risk spacing 24-35 and age <18 1.26 1.12 1.42 1.16 1.02 1.32 1.01 0.82 1.24 

Double risk spacing <24 and age 40+ 1.99 1.10 3.60 2.09 1.11 3.95 1.86 0.79 4.40 

Double risk spacing 24-35 and age 40+ 1.04 0.55 1.97 1.46 0.77 2.79 0.78 0.24 2.50 

3-way risk spacing <24, order 4+, age<18 2.55 1.23 5.30 1.15 0.48 2.73 0.40 0.05 2.97 

3-way risk spacing <24, order 4+, age 40+ 1.39 1.22 1.58 1.22 1.06 1.41 0.97 0.77 1.21 

3-way risk spacing 24-35, order 4+, 

age<18 

1.16 0.29 4.60 0.93 0.19 4.48 nc nc nc 

3-way risk, spacing 24-35, order 4+, age 

40+ 

1.31 1.20 1.43 1.24 1.13 1.37 1.00 0.86 1.16 

Total N 348,122 348,122 348,740 

(Continued...)
51 

Table 17. – Continued

Note: The adjusted models included the following variables: 

Sex of index child, urban–rural area of residence, wantedness of child, mother’s education, whether conception 

was a result of contraceptive failure, outcome of preceding pregnancy (live birth or stillbirth), type of provider of 

prenatal care, type of provider of delivery assistance, number of prenatal tetanus injections, timing of first prenatal 

care visit, quintile of DHS Wealth Index, type of water supply, type of toilet facility, possession of refrigerator, 

duration of pregnancy, and whether preceding child died before conception of index child. 

nc: no cases stunted, underweight, or wasted 

The effects on children’s nutritional status of having more than one risk factor at a time are shown in 

Table 17 for individual combinations, in Table 18 for the number of combinations, and in Figure 8 for 

stunting by significant combinations of risk factors. Children were most likely to be stunted if the 

preceding birth–to–conception interval was fewer than 24 months, the birth order was four or more, and 

the mother was under 18 years of age at the time of birth (as noted above, a very rare combination). 

Children who were born to mothers age 40 or over and with a spacing interval of fewer than 24 months 

had almost twice the odds of being stunted as children with no extra risk factor. On the other hand, 

children whose mothers were 40 or over at the time of their birth and with no other risk factor had a 23 

percent lower likelihood of being stunted than children in the reference category. Most of the common 

combinations, those with 1 percent or more of births, had increased risks of stunting: single risks of 

intervals less than 24 months (45 percent greater risk of stunting) and intervals of 24–35 months (20 

percent greater); and double risks of intervals of fewer than 24 months with a birth order four or higher 

(50 percent greater), intervals of 24–35 months with a birth order four or higher (25 percent greater), first 

births to mothers under 18 years of age (11 percent greater), and births with an interval of fewer than 24 

months to mothers under 18 years of age (53 percent greater risk of stunting). 

The effects of the combinations for underweight are very similar to those for stunting. None of the 

combinations are significantly related to wasting except for the unavoidable first–birth category that has 5 

percent greater odds of being stunted than the reference category. 

The odds of being stunted, underweight, and wasted increase with the number of risk factors, even after 

controlling for confounding variables (Table 18). Having three risk factors increases the odds of stunting 

by 80 percent, the odds of underweight by 65 percent, and the odds of wasting by 28 percent in 

comparison to the reference group of having no extra risk factor. However, just being a first birth does not 

significantly change the odds of being wasted compared with no risk factors. 
52 

Table 18. Adjusted odds ratios for stunting, underweight, and wasting by the mother’s fertility–

related risk, living children age 0 to 59 months at survey, 45 DHS surveys, 2006–2012 

 Stunting Underweight Wasting 

 aOR CI- CI+ aOR CI- CI+ aOR CI- CI+ 

Extra risk due to fertility pattern 

No extra risk (ref.) 1.00 1.00 1.00 

Unavoidable first-birth risk 1.01 0.99 1.04 1.06 1.02 1.09 1.11 1.06 1.17 

Any single risk 1.13 1.10 1.16 1.12 1.09 1.15 1.01 0.97 1.05 

Any double risk 1.24 1.21 1.27 1.20 1.17 1.24 1.01 0.97 1.06 

Any 3-way risk 1.31 1.22 1.41 1.22 1.13 1.33 0.99 0.87 1.12 

Total N 348,122 348,122 348,740 

Note: The adjusted models included the following variables: 

Sex of index child, urban–rural area of residence, wantedness of child, mother’s education, whether conception 

was a result of contraceptive failure, outcome of preceding pregnancy (live birth or stillbirth), type of provider of 

prenatal care, type of provider of delivery assistance, number of prenatal tetanus injections, timing of first prenatal 

care visit, quintile of DHS Wealth Index, type of water supply, type of toilet facility, possession of refrigerator, 

duration of pregnancy, and whether preceding child died before conception of index child. 

Figure 8. Adjusted relative odds of stunting by combinations of fertility behavior risk factors, 42 

DHS surveys between 2006 and 2012 

2.55

1.99

1.53 1.50 1.45 1.39 1.31 1.26 1.25 1.20

1.11

0.77

0.00

0.50

1.00

1.50

2.00

2.50

3.00
53 

Discussion 

Previous studies have well established the importance of the length of the preceding birth interval to the 

survival chances of a child through the neonatal, infant, and under–five years periods of life. The previous 

papers by the first author indicated that there is an optimal length of birth interval, namely, 36–59 months 

birth to birth. The current study extends and strengthens the analyses presented in those papers by: 

• Adding analyses of two other fertility risk behavior characteristics: the mother’s age at the child’s 

birth and the birth order of the child; 

• Analyzing a newer large data set, with 1,227,151 births (424,948 for neonatal and infant 

mortality, 1,176,384 for under age five multivariate analyses of mortality, and 348,769 living 

children under age five for stunting); 

• Using all 45 surveys in the DHS program that took place between 2006 and 2012 for mortality 

analysis; using all 42 surveys with data on nutritional status; 

• Using only unimputed data on birth–to–conception interval and singleton births; and 

• As in the 52–country study (Rutstein 2008), for mortality analyses, using Cox proportional 

hazards regression to include additional data for children only partially exposed to the risk of 

mortality. 

In general, the findings of this study confirm those of the first author’s prior studies based on 17 and 52 

different surveys (Rutstein 2008; Rutstein 2005). For neonatal mortality, the adjusted risk ratios indicate 

that risk of dying decreases with increasing birth–to–conception interval lengths up to 18 months13 and 

rises again for conceptions after 48 or more months. This rise was indicated in the previous studies for 

birth intervals of five and more years, but the increase was not statistically significant in the 17–country 

study. The larger data sets now confirm that this rise is statistically significant for intervals of four or 

more years. 

As in the 17–survey and 52–survey papers, the results for infant mortality are similar to those of neonatal 

mortality with the exception that the spacing interval of 18–23 months also has increased risk that is 

significant. For post–neonatal mortality, the fall of the risk of dying with increasing interval is again 

similar to those of early neonatal, neonatal, and infant mortality. Unlike the previous studies, however, 

there is an increase with duration of interval for children conceived 60 or more months after a preceding 

birth with 48–59 months being close to significant. 

For the risk of dying between ages one and four years, also known as child mortality, the adjusted risk 

ratios indicate that the longer the birth interval, the lower the risk, even for intervals of 48 or more 

months. Similar results were found in the 52–country study. 

For under–five mortality, which includes the effects of neonatal, post–neonatal, and child mortality, there 

are significant declines in risk as the interval increases up to the 60–95–month duration group. A 

significant small rise in risk is seen for conceptions occurring 96 or more months after a prior birth, 

shown by the 52–survey study as well. 

 

13 The risk of dying decreases up to 29 months, but the decreases are not significant at the 95 percent level between 

18-29 months. 
54 

Mother’s age at birth has a U–shaped relationship with early neonatal, neonatal, post–neonatal, and infant 

mortality. This relationship persists even after adjusting for the preceding birth–to–conception interval, 

the child’s birth order, and other potential confounders. Children born to young mothers (under age 18), 

for example, have a 20 percent greater risk of dying in the first year of life, and children born to mothers 

ages 35–39 and 40 or older have a 20 percent and 50 percent greater risk of dying in the first year of life, 

respectively. A different relationship is evident for mortality at age one to four years as the risk of dying 

decreases with increasing maternal age. It may be that the greater life experience of older mothers 

overcomes the biological effects of older age at birth for children older than 12 months. 

Birth order is not significantly related to mortality during the neonatal period. After the neonatal period, 

however, increasing birth order results in increasing risk of dying, once confounding factors have been 

taken into account. 

The more risk factors a child faces, the greater the risk of mortality, and certain combinations are 

especially deleterious to survival. The risk of being chronically malnourished (stunted or underweight) 

decreases with increasing time between the preceding birth and the conception of the child under study. In 

contrast with the effects on mortality, no leveling or increase occurs in the risk of being stunted or 

underweight for long birth intervals. No significant relationship exists between birth interval length and 

wasting. This lack of association is not surprising given that wasting is an indicator of acute malnutrition 

and is more likely to occur because of a recent shortage of food or a recent illness. The results for stunting 

and underweight are similar to those found in the earlier 17–survey and 52–survey studies and for some 

studies in the systematic literature review by Dewey and Cohen (2007). 

Increasing mother’s age at birth lowers a child’s risk of being stunted, but increasing birth order increases 

the risk. The risk of being underweight also decreases with mother’s age at birth. Birth order is not related 

to being underweight once confounding factors have been taken into account. The number of risk factors 

a child faces increases the risk of chronic malnutrition (stunting and underweight) but is unrelated to 

wasting, similar to that found for the risk factors considered individually. 

Members of the World Health Organization meeting who reviewed the previous 17–country article 

expressed concern about the mechanisms by which the length of intergenesic intervals could affect child 

mortality. The results shown for stunting and underweight (chronic and overall undernutrition) in the 

previous 52–survey study and those shown here indicate one pathway may be through children’s 

nutritional status and could indicate that the ability to properly care for closely spaced children is a key 

factor. Even the pattern of acute malnutrition (wasting) may be the result of the joint impact of 

undernutrition and mortality, since children who were more severely wasted (with odds of wasting higher 

than those of the reference group) may have passed away and were therefore not around to be measured. 

The current large data set indicates that intervals longer than those traditionally acknowledged as having 

high risk, fewer than 24 months between births or fewer than 15 months birth–to–conception, have 

substantial impacts on the risks of mortality and of undernutrition. In this study, intervals of 18–23 

months between the prior birth and the conception of the index child (equivalent to 27– to 32–month 

birth–to–birth intervals) have statistically significant elevated risks for early neonatal, neonatal, infant, 

child, and under–five mortality. Intervals of 18–23 months have elevated risks for post–neonatal mortality 

as well but the result is not quite at the 5 percent significance level. Intervals up through 35 months birth–

to–conception (up through 44 months birth–to–birth) have significant elevated risks of child and under–

five mortality. 

Although the excess risk of mortality is highest for very short intervals (fewer than 12 months birth–to–

conception), relatively few children are conceived at such intervals (13 percent). Combining both the 

increased risk of death for children conceived between 12 and 35 months with the great number of 
55 

children with such intervals (42 percent) results in substantial potential declines in mortality by avoiding 

these intervals. Population–attributable risks (PARs) of under–five mortality are shown in Table 19 for 

intervals of fewer than 36 months between conception and the prior birth, for mother’s age at birth under 

18 years or 40 years or over, and for births of order four or higher. 

The PAR for under–five mortality for avoiding conceptions at fewer than 36 months after a birth is 0.26. 

In other words, if all women would wait at least 36 months to conceive again, under–five deaths would 

fall by 26 percent. The PAR for mother’s age at birth under age 18 or 40 or over is 0.03 and 0.04 for birth 

order four or higher. Taken together, under–five mortality could be reduced by one third if women 

would wait at least 36 months to conceive again, have their children between ages 18–39 years, and 

not have more than three children. 

Finally, Figures 7, 8, and 9 show the effects of the preceding birth–to–conception interval, mother’s age at 

the child’s birth, and the child’s birth order on the likelihood of having a living and thriving child. The 

figures show the relative risks for children to be both alive and not stunted. Clearly, the likelihood for 

children to survive and not be stunted is lowest for birth–to–conception intervals of fewer than 12 months 

and increases rapidly as the duration of the interval increases. Parents who want their children to 

survive and thrive would do well to wait at least 30 months after a birth to conceive another child. 

Similarly, the optimal age for a mother to have her children born is between 25–39 years of age, 

and births before 18 years of age should be avoided. The likelihood of being alive and not stunted 

decreases as birth order increases, becoming worse for children with orders higher than four. 

Table 19. Calculation of population–attributable risks for infant and under–five mortality by 

duration of preceding birth–to–conception interval, mother’s age at child’s birth, and the birth 

order, 45 DHS surveys, 2006–2012 

 

Under–five mortality among children born 60 to 179 months prior to interview 

Average 

U5MR Total births 

Pooled* 

b se RR PAR Total deaths 

Preceding birth–to–conception interval 

<36 months 0.111 509,421 0.59 0.01 1.80 0.26 56,546 

36+ months (ref.) 0.054 345,800 0.00 0.00 1.00 0.00 18,673 

first births 0.088 321,163 0.63 0.01 1.88 0.19 28,262 

Total** 0.088 1,176,384 103,481 

Mother’s age at birth 

<18 or 40+ years 0.128 127,866 0.26 0.01 1.30 0.03 16,367 

18–39 years (ref.) 0.083 1,048,518 0.00 0.00 1.00 0.00 87,027 

Total 0.088 1,176,384 103,394 

Birth order 

1–3 birth order (ref.) 0.081 771,608 0.00 0.00 1.00 0.00 62,500 

4+ birth order 0.103 404,776 0.12 0.01 1.13 0.04 41,692 

Total 0.089 1,176,384 104,192 

U5MR: under–five mortality rate 

b: weighted average coefficient; se: weighted average standard error of b 

RR: adjusted relative risk; PAR: Population–attributable risk 

* Weighted average using inverse of square of standard error as weights 

** Total excludes 2770 births with missing birth interval data 
56 

Figure 9. Adjusted relative risk of being alive and not stunted at five years of age, by duration of 

preceding birth–to–conception interval

0.22

0.32

0.42

0.57

0.72

0.88

1.00

1.10 1.11

1.02

0.00

0.20

0.40

0.60

0.80

1.00

1.20

<6 6-11 12-17 18-23 24-29 30-35 36-47

reference

 48-59 60-95 96+

Adjusted relative risk

Months
57 

Figure 10. Adjusted relative risk of being alive and not stunted at five years of age, by mother’s 

age at child’s birth 

0.69

1.00

1.10 1.10

1.02

0.00

0.20

0.40

0.60

0.80

1.00

1.20

< 18 18 to 24 reference 25 to 34 35 to 39 40+

Adjusted relative risk

Age in years

18 to 24 

reference
58 

Figure 11. Adjusted relative risk of being alive and not stunted at five years of age, by child’s birth 

order

1.00

0.91

0.81

0.73

0.00

0.20

0.40

0.60

0.80

1.00

1.20

 1-2 reference 3-4 5-6 7+

Adjusted relative risk

Birth order

1-2 

reference
59 

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63 

Appendix 

Appendix Table A1. Distribution of births 0 to 179 months and 0 to 59 months prior to survey by 

control variables used in multivariate analyses, 45 DHS surveys, 2006-2012 

 

Births 0 to 179 months 

prior to the survey 

Births 0 to 59 months 

prior to the survey 

Control variables Percent Frequency Percent Frequency 

Control variables included in all multivariate models 

Sex of index child 

Male 51.2 628,039 51.1 217,328 

Female 48.8 599,122 48.9 207,620 

Type of place of residence 

Urban 33.5 411,419 33.3 141,657 

Rural 66.5 815,742 66.7 283,291 

Mother's highest educational level 

No education 38.1 466,938 34.1 144,766 

Primary 32.2 395,385 32.2 136,621 

Secondary 24.3 297,976 27.6 117,426 

Higher 5.4 66,819 6.1 26,123 

Wealth index quintiles 

Poorest quintile 24.9 305,817 24.8 105,404 

Second quintile 21.5 263,481 21.4 90,928 

Middle quintile 19.8 242,885 19.8 84,253 

Fourth quintile 18.2 223,120 18.2 77,274 

Wealthiest quintile 15.6 191,858 15.8 67,089 

Household has refrigerator 

No 77.4 950,149 77.9 330,994 

Yes 20.7 254,142 19.4 82,310 

Missing 1.9 22,870 2.7 11,644 

Type of toilet/latrine 

Flush toilet 27.0 331,922 25.4 107,990 

Pit latrine 37.5 460,583 38.8 164,854 

None 29.5 362,191 29.2 124,102 

Other, missing 5.9 72,465 6.6 28,002 

Source of drinking water 

Piped 35.6 437,419 34.7 147,246 

Open well 17.8 218,486 17.1 72,702 

(Continued...)
64 

Appendix Table A1. – Continued 

 

Births 0 to 179 months 

prior to the survey 

Births 0 to 59 months 

prior to the survey 

Control variables Percent Frequency Percent Frequency 

Protected well 18.4 225,511 18.7 79,652 

Surface 16.2 198,721 16.8 71,187 

Rain 1.5 18,931 1.5 6,344 

Tanker truck 1.1 13,825 1.1 4,638 

Bottled 2.8 34,145 2.8 11,730 

Other, missing 6.5 80,123 7.4 3,931 

Length of gestation (months) 

7 .9 10,601 0.6 2,610 

8 1.7 21,380 2.2 9,374 

9 92.3 1,132,069 90.9 386,251 

10 or more 5.1 63,111 6.3 26,713 

Survival of preceding child 

Did not die 93.6 1,148,574 94.4 401,045 

Preceding child died 6.4 78,587 5.6 23,903 

Additional control variables included in models predicting early neonatal, neonatal, post-neonatal, and 

infant mortality 

Outcome of preceding pregnancy 

Live birth 62.5 265,752.0 

Not a live birth 33.9 143,990.0 

Not available 3.6 15,206.0 

 

Time wanted pregnancy 

Then 73.0 310,405.0 

Later 16.0 67,907.0 

No more 10.5 44,793.0 

NA 0.4 1,843.0 

 

Pregnancy was result of contraceptive failure 

No 95.6 406,136.0 

Yes 2.4 10,272.0 

Not asked 2.0 8,540.0 

 

Prenatal care provider 

Doctor 14.9 63,264 

Nurse/Midwife 30.4 129,359 

Other Medical 13.7 58,245 

TBA 2.4 10,199 

(Continued...)
65 

Appendix Table A1. – Continued 

 

Births 0 to 179 months 

prior to the survey 

Births 0 to 59 months 

prior to the survey 

Control variables Percent Frequency Percent Frequency 

Other Person 28.7 122,128 

No One 9.8 41,753 

 

Delivery care provider 

Doctor 9.1 38,863 

Nurse/Midwife 33.7 143,056 

Other Medical 14.7 62,425 

TBA 21.3 90,442 

Other Person 17.5 74,253 

No One 3.7 15,909 

 

Prenatal tetanus injections 

None 17.4 74,111 

One 14.3 60,617 

2+ 39.1 166,226 

Missing, DK 29.2 123,994 

 

Timing of first antenatal check 

No antenatal check 39.4 167,464 

 < 3 months 15.5 65,661 

3-4 months 24.8 105,217 

5-6 months 15.5 65,987 

7-8 months 4.2 17,688 

Ninth month 0.3 1,245 

Doesn't know 0.4 1,645 

Total 100.0 1,227,161 100.0 424,948 

Note: Distributions and percentages are based on unweighted cases, since the application of standard individual 

country weights is not meaningful in the merged sample. Forty-three cases had missing information on maternal 

education, and 41 cases had missing information on timing of first antenatal check.