# Association between Infant Feeding and Early Postpartum Infant Body Composition: A Pilot Prospective Study

Authors: Alex Kojo Anderson
Journal: International Journal of Pediatrics
 (2009)

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## Abstract

Research studies have produced conflicting results of the impact of breastfeeding on overweight/obesity. This study evaluated the impact of infant feeding on infant body composition. There were two groups of mother-infant pairs (exclusive breastfeeding [EBF;n=27] and mixed feeding [MF; n=13]) in this study. At baseline, participants were similar in their demographic characteristics except prepregnancy weight, where MF mothers tended to be heavier than their EBF counterparts (67.3 kg versus 59.9 kg; P=.034). Infant birth weight was slightly higher among the MF group than their EBF counterparts (3.5 kg versus 3.4 kg), although the differences were not statistically significant. At 3 months postpartum, mean infant FMI (4.1 kg/m2 versus 3.8 kg/m2) and percent body fat (24.4% versus 23.1%) were slightly higher among EBF infants than MF infants. In terms of growth velocity, EBF infants gained weight faster than their MF counterparts, although the differences were not statistically significant. The findings from this study suggest that EBF may promote faster weight gain and increase in both fat mass index (FMI) and percent body fat in the early postpartum period in addition to the numerous health benefits enjoyed by the infant and the mother who exclusively breastfeeds her newborn.


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## Body

## 1. Introduction

A number of primary and review
articles provide strong evidence of the protective effect of breastfeeding against
overweight/obesity [1–9].
Despite this strong evidence, other studies have reported an inverse
relationship or no relationship at all between breastfeeding and
overweight/obesity [10]. A 2003 narrative review of
the literature by Dewey reported a protective effect of breastfeeding against
childhood obesity [11]. Another systematic review by
Owen et al. [5] reported an inverse
association between breastfeeding and obesity even after adjusting for known
confounding factors (parental obesity, maternal smoking, and social class).
Other researchers have also observed an inverse association as well as
dose-response association between duration of breastfeeding and risk of
overweight/obesity [4]. Balaban and Silva in their
review have suggested a small, but significant, protective effect of
breastfeeding against childhood overweight and obesity [12]. Studies by Wadsworth et al. [13], O'Callaghan et al. [14], and Zive et al. [15] have reported no association
between breastfeeding and childhood adiposity, while Agras et al.
[16] report breastfeeding as a risk factor for
greater adiposity during childhood. While meta-analysis and systematic reviews
suggest a small to moderate protection against overweight by breastfeeding,
these benefits may not extend to adulthood [3, 4, 11, 12, 17].
Furthermore, a recent randomized control trial conducted in Belarus did not
show any benefit of prolonging exclusive breastfeeding on height, BMI, and
adiposity during childhood [18]. The inconclusiveness of the
literature, therefore, raises the question of how these studies were conducted,
indicators of overweight/obesity measured, definition of breastfeeding used,
and how infant feeding data were obtained as well as the design of the
respective studies. Definition of breastfeeding has not been consistent across
the studies, and breastfeeding data have been collected retrospectively,
sometimes more than 5 years after the actual practice. Again, overweight/obesity
was assessed via body mass index (BMI) and sometimes via skin-fold
measurements. Although, the BMI is an appropriate screening tool for
overweight/obesity, it is not adequate enough in predicting adiposity which is
directly associated with poor health outcomes such as cardiovascular diseases
(CVDs). Skin-fold measurements also used to assess adiposity come with a number
of associated errors such as technician errors in measurement and instrument
error. As such, it is important to consider all these factors in making a
conclusive determination regarding the protective effect of breastfeeding
against overweight/obesity. Therefore, these limitations of earlier studies
evaluating the association between infant feeding and obesity will continue to
cast doubts on the relationship between breastfeeding and overweight/obesity.The purpose of this study was to
prospectively examine the association between infant feeding and overweight and
adiposity among infants in the early postpartum weeks in a pilot study. This
provides a unique opportunity to explore the association between exclusive
breastfeeding and infant adiposity measured by the PEA POD body composition
system. In addition, unlike earlier studies that assessed breastfeeding data
retrospectively, this study assessed infant feeding prospectively alongside
body composition measurements.


## 2. Materials and Methods

### 2.1. Study Design

This was a prospective pilot study
conducted in Athens-Clarke County and surrounding counties in the state of Georgia
between
November 2005 and July 2008. The study protocol was approved by the Human
Subjects Institutional Review Boards (IRBs) of the University of Georgia (UGA)
and the Athens Regional Medical Center (ARMC). Additionally, written informed
consent was obtained from mothers before the birth of each participating
infant. Subjects were newborns of singleton deliveries of women recruited in
their third trimester of pregnancy. Characteristics as well as exclusion and
inclusion criteria of mothers are reported elsewhere [19]. Briefly, mothers of these
infants were recruited during pregnancy but not later than 36 weeks gestation. Newborns were
screened after delivery for inclusion in the present study. Exclusion criteria
included preterm (<37 weeks gestation), low birthweight (<2500 grams),
and neonates with anomalies requiring them to spend more than 24 hours in the
neonatal intensive care unit(NICU).


### 2.2. Study Implementation

Baseline data was collected at the
time of recruitment and follow-up at 2, 4, 8, and 12 weeks postpartum. Infant
anthropometric and body composition measurements were completed at 2, 4, 8, and
12 weeks postpartum in the Maternal and Child Nutrition Research Lab (MCNRL),
Department of Foods and Nutrition, the University of Georgia (UGA), Ga, USA. Mothers of
participating infants were interviewed using a structured questionnaire
containing both closed- and open-ended questions. The study was originally
designed to compare weight and body composition of infants who were either
exclusively breastfed or formula fed. It was later realized that infants in the
formula feeding group received some amount of breastmilk and hence were
classified as mixed feeding.


### 2.3. Anthropometric and Body Composition Measurements

Infant anthropometric measurements
were conducted with a calibrated scale attached to the PEA POD for weight (Life
Measurement Inc., Concord, Calif,
USA) to the nearest 0.0001 kg and an infantometer (Seca 416) for length
measurement to the nearest 0.1 cm. Both birthweight and birth length were
reported by mothers.Body composition made up of fat mass
and fat-free mass was measured using the PEA POD body composition system
following the manufacturers' protocol for body composition measurement (Life
Measurement Inc. Concord, Calif,
USA). The PEA POD is a pediatric air-displacement plethysmograph which
assesses the body composition of infant birth through 6 months old by direct
measurement of body mass and body volume using the principle of whole body
densitometry. The description and operation of the PEA POD are reported elsewhere [20]. Before each body composition
measurement, the infant's length is measured and inputted into the PEA POD
computer system. The length imputed into the computer system is used to
quantify the isothermal volume of air close to the infant's skin and lungs. All
subjects were tested nude, and their hair was smoothed down with baby oil. This
is to allow for precise quantification of the amount of air behaving
isothermally in the test chamber to ensure accurate measurement according to
the manufacturer of the PEA POD. Each body composition measurement in the test
chamber lasted approximately 2 minutes. The within-day mean (±SD)
reproducibility of infant percent body fat values measured with the PEA POD is
0.4±1.8% in the Maternal and Child Nutrition Research Lab, Department of Foods and Nutrition, University
of Georgia, Ga, USA.


### 2.4. Outcome Variables

The primary outcome variables were
percent infant body fat and total body weight at the different time points.
Changes in percent body fat and total body weight were estimated from one time
point to the other.


### 2.5. Statistical Analysis

All data entry and analyses were
performed using SPSS for Windows version 16.0 (SPSS Inc. Chicago, Ill, USA). Fat mass index
(FMI) as a measure of infant adiposity was computed by the formula “fat mass in
kilograms divided by the square of infant length in meters”, while fat-free
mass index (FFMI) was computed by the formula “fat-free mass in kilograms
divided by the square of infant length in meters”. Differences in variables by
group were evaluated usingt-tests and analysis of variance (ANOVA) for
continuous variables. Chi-square analyses were used to examine bivariate
associations between categorical variables. Repeated measures analysis was used
to test the effects of type of infant feeding on weight and body composition
(fat mass, fat-free mass, FMI, and FFMI) values. Pearson r was used to
determine correlation between continuous variables and infant total body weight
and percent body fat. The level for statistical significant was set at P=.05.


## 2.1. Study Design

This was a prospective pilot study
conducted in Athens-Clarke County and surrounding counties in the state of Georgia
between
November 2005 and July 2008. The study protocol was approved by the Human
Subjects Institutional Review Boards (IRBs) of the University of Georgia (UGA)
and the Athens Regional Medical Center (ARMC). Additionally, written informed
consent was obtained from mothers before the birth of each participating
infant. Subjects were newborns of singleton deliveries of women recruited in
their third trimester of pregnancy. Characteristics as well as exclusion and
inclusion criteria of mothers are reported elsewhere [19]. Briefly, mothers of these
infants were recruited during pregnancy but not later than 36 weeks gestation. Newborns were
screened after delivery for inclusion in the present study. Exclusion criteria
included preterm (<37 weeks gestation), low birthweight (<2500 grams),
and neonates with anomalies requiring them to spend more than 24 hours in the
neonatal intensive care unit(NICU).


## 2.2. Study Implementation

Baseline data was collected at the
time of recruitment and follow-up at 2, 4, 8, and 12 weeks postpartum. Infant
anthropometric and body composition measurements were completed at 2, 4, 8, and
12 weeks postpartum in the Maternal and Child Nutrition Research Lab (MCNRL),
Department of Foods and Nutrition, the University of Georgia (UGA), Ga, USA. Mothers of
participating infants were interviewed using a structured questionnaire
containing both closed- and open-ended questions. The study was originally
designed to compare weight and body composition of infants who were either
exclusively breastfed or formula fed. It was later realized that infants in the
formula feeding group received some amount of breastmilk and hence were
classified as mixed feeding.


## 2.3. Anthropometric and Body Composition Measurements

Infant anthropometric measurements
were conducted with a calibrated scale attached to the PEA POD for weight (Life
Measurement Inc., Concord, Calif,
USA) to the nearest 0.0001 kg and an infantometer (Seca 416) for length
measurement to the nearest 0.1 cm. Both birthweight and birth length were
reported by mothers.Body composition made up of fat mass
and fat-free mass was measured using the PEA POD body composition system
following the manufacturers' protocol for body composition measurement (Life
Measurement Inc. Concord, Calif,
USA). The PEA POD is a pediatric air-displacement plethysmograph which
assesses the body composition of infant birth through 6 months old by direct
measurement of body mass and body volume using the principle of whole body
densitometry. The description and operation of the PEA POD are reported elsewhere [20]. Before each body composition
measurement, the infant's length is measured and inputted into the PEA POD
computer system. The length imputed into the computer system is used to
quantify the isothermal volume of air close to the infant's skin and lungs. All
subjects were tested nude, and their hair was smoothed down with baby oil. This
is to allow for precise quantification of the amount of air behaving
isothermally in the test chamber to ensure accurate measurement according to
the manufacturer of the PEA POD. Each body composition measurement in the test
chamber lasted approximately 2 minutes. The within-day mean (±SD)
reproducibility of infant percent body fat values measured with the PEA POD is
0.4±1.8% in the Maternal and Child Nutrition Research Lab, Department of Foods and Nutrition, University
of Georgia, Ga, USA.


## 2.4. Outcome Variables

The primary outcome variables were
percent infant body fat and total body weight at the different time points.
Changes in percent body fat and total body weight were estimated from one time
point to the other.


## 2.5. Statistical Analysis

All data entry and analyses were
performed using SPSS for Windows version 16.0 (SPSS Inc. Chicago, Ill, USA). Fat mass index
(FMI) as a measure of infant adiposity was computed by the formula “fat mass in
kilograms divided by the square of infant length in meters”, while fat-free
mass index (FFMI) was computed by the formula “fat-free mass in kilograms
divided by the square of infant length in meters”. Differences in variables by
group were evaluated usingt-tests and analysis of variance (ANOVA) for
continuous variables. Chi-square analyses were used to examine bivariate
associations between categorical variables. Repeated measures analysis was used
to test the effects of type of infant feeding on weight and body composition
(fat mass, fat-free mass, FMI, and FFMI) values. Pearson r was used to
determine correlation between continuous variables and infant total body weight
and percent body fat. The level for statistical significant was set at P=.05.


## 3. Results

### 3.1. Participant Characteristics

Of the 40 infants who participated in
this study, 27 were exclusively breastfed, while the remaining 13 were mixed
fed by 12 weeks postpartum. All infants in the mixed feeding group were
introduced to infant formula on day 1 after delivery in addition to some
breastmilk. The proportion of nonbreastmilk feed received by the mixed feeding
group ranged from 10% to 100% of their total food intake across the study
period. Majority of the infants in the mixed feeding group received on the
average 50% to 70% of their total daily food intake from nonbreastmilk
substitutes such asSimilac Advance,
Isomil, Infamil, and Gerber Rice Cereal. For the exclusively breastfeeding
infants, they received only breastmilk as the sole source of nutrients, no
water or other fluids through the 12 weeks of follow-up.Descriptive statistics of the
participants are presented in Table1. Average age for mothers at delivery was
29.95±5.04 (range 19–42) years with exclusively breastfeeding
mothers being slightly older than their mixed feeding counterparts. Years of
formal education were
comparable between the two groups of mothers. Most of the mothers in both
groups were married, white/Caucasian, and either employed full time or part time.
Mean gestation age was 39.39±0.87 (37–41) weeks, with
no statistical difference in gestational age between the exclusively
breastfeeding mothers and mixed feeding mothers and also by gender of the child
(Table 1). There were no significant differences in both maternal and infant
parameters between the two groups except for maternal prepregnancy weight, prepregnancy
BMI, and maternal weight at delivery. Mothers of infants who received mixed
feeding reported higher prepregnancy weight (P=.034), prepregnancy BMI (P=.011),
and also weighed more at delivery (P=.033) than mothers of exclusively
breastfeeding infants (Table 1). The infants were identical in birth weight and
birth length in addition to gestational age. The mean birth weight was 3.47±0.42 (range 2.51–4.26) kilograms,
while mean birth length was 51.36±2.06 (of range 46.99–54.61)
centimeters. There were no significant differences in birth weight and birth
length between exclusively breastfeeding and mixed feeding infants.Table 1
Characteristics of mothers and infants according to
type of feeding.
Maternal characteristicsEBF (n=27)MF (n=13)P-valueAge (years)30.78±5.1628.23±4.48NSYears of schooling17.44±2.2617.31±3.30NSMaternal height (m)1.64±0.071.61±0.06NSMaternal prepregnancy weight (kg)59.90±8.2867.27±12.86.034Prepregnancy BMI (kg/m2)22.21±2.7726.15±6.59.011Maternal weight at delivery (kg)75.13±9.6882.66±10.91.033Pregnancy weight gain (kg)15.10±3.9515.42±4.52NSGestational age at delivery (weeks)39.46±0.8639.25±0.90NSn (%)n (%)Marital StatusNSMarried25 (92.6)11 (84.6)Single2 (7.4)2 (15.4)EthnicityNSWhite/Caucasian24 (88.9)10 (76.9)Black/African American3 (11.1)3 (23.1)Employment statusNSFull time15 (55.6)8 (61.5)Part time7 (25.9)4 (30.8)Not working5 (18.5)1 (7.7)Type of deliveryNSVaginal/spontaneous23 (85.2)8 (69.2)Cesarean4 (14.8)4 (30.8)Infant characteristicsBirth weight (kg)3.44±0.423.52±4.33NSBirth length (cm)51.36±2.0351.34±2.20NSGenderNSBoys15 (55.6)7 (53.8)Girls12 (44.4)6 (46.2)EBF: exclusive breasfeeding; MF: mixed feeding.Vaginal/spontaneous delivery was higher among exclusively breastfeeding infants
with cesarean delivery being higher among mixed feeding infants, although the
differences were not statistically significant (Table1).


### 3.2. Type of Feeding and Early Growth of Infant

There was a modest increase in body
weight across the feeding groups with time. Exclusively breastfeeding infants
tended to gain slightly more weight with time compared to mixed feeding
infants, although the differences in weight gain across time were not statistically
significant (Figure1). As depicted in Figure 1, the difference in weight gain
between the two groups became more prominent at 8 (117.7 grams) and 12 (81.6
grams) weeks postpartum compared to the difference at 2 (16.9 grams) and 4
(12.7 grams) weeks postpartum with respect to birth weight. A similar trend was
seen for infant length with exclusively breastfeeding infants gaining more
length than mixed feeding infants even though the difference was not
significant (data not shown).Figure 1
Changes in infant body weight with respect to
birth weight (EBF: exclusive breastfeeding; MF: mixed
feeding).


### 3.3. Type of Feeding and Early Infant Body Composition

The results from this study showed
gradual increase in the body composition (fat mass, fat-free mass, fat mass
index [FMI], and fat-free mass index [FFMI]) of infants with time. There were,
however, some differences in the accumulation of fat mass and fat-free mass. Exclusively
breastfeeding infants accumulated more fat mass compared to their mixed feeding
counterparts, whereas mixed feeding infants gained more fat-free mass compared
to exclusively breastfeeding infants, although the difference was not
statistically significant (data not shown). As shown in Figure2, both groups
started with about the same value for FMI at 2 weeks postpartum but with time
the data showed slight differences although these were not statistically
significant. Further examination of the data showed that exclusively
breastfeeding infants gained slightly more FMI at 4 (0.93 kg/m2 versus
0.84 kg/m2), 8 (1.92 kg/m2 versus 1.68 kg/m2),
and 12 (2.34 kg/m2 versus 2.10 kg/m2) weeks postpartum
with respect to their FMI as computed at 2 weeks postpartum compared to mixed
feeding infants (Figure 2). The results, therefore, show that by 12 weeks postpartum, infants
who are exclusively breastfeeding have a mean FMI which is at least 0.2 unit higher than infants
who are mixed feeding which is also an indication of higher adiposity among
exclusively breastfeeding infants compared to mixed feeding infants. For FFMI
which is a measure of infant lean mass, Figure 3 shows that unlike adiposity
mixed feeding infants tended to have higher amounts of lean mass at 2 weeks
postpartum and throughout the 12 weeks of follow-up compared to the exclusive
breastfeeding counterparts. Mean FFMI gains were 0.13 kg/m2 versus 0.12 kg/m2,
0.51 kg/m2 versus 0.65 kg/m2, and 0.39 kg/m2 versus
0.60 kg/m2 at 4, 8, and 12 weeks postpartum with respect to FFMI at
2 weeks postpartum for exclusively breastfeeding and mixed feeding infants,
respectively.Figure 2
Pattern of infant adiposity with time (EBF: exclusive breastfeeding; MF: mixed
feeding).Figure 3
Pattern of infant lean mass with time (EBF: exclusive breastfeeding; MF: mixed
feeding).The repeated measures analysis did not show any significance between group differences in
infant weight, length, fat mass, fat-free mass, FMI, FFMI, and percent body fat.
Adjusted for birthweight, birth length and infant gender, fat mass, fat-free
mass, FMI, and FFMI did not differ significantly between exclusively
breastfeeding and mixed feeding infants at 2, 4, 8, and 12 weeks postpartum.
There was a strong correlation between the computed FMI and the measured percent
body fat (r=0.949 to 0.974; P<.001) at each time point.


## 3.1. Participant Characteristics

Of the 40 infants who participated in
this study, 27 were exclusively breastfed, while the remaining 13 were mixed
fed by 12 weeks postpartum. All infants in the mixed feeding group were
introduced to infant formula on day 1 after delivery in addition to some
breastmilk. The proportion of nonbreastmilk feed received by the mixed feeding
group ranged from 10% to 100% of their total food intake across the study
period. Majority of the infants in the mixed feeding group received on the
average 50% to 70% of their total daily food intake from nonbreastmilk
substitutes such asSimilac Advance,
Isomil, Infamil, and Gerber Rice Cereal. For the exclusively breastfeeding
infants, they received only breastmilk as the sole source of nutrients, no
water or other fluids through the 12 weeks of follow-up.Descriptive statistics of the
participants are presented in Table1. Average age for mothers at delivery was
29.95±5.04 (range 19–42) years with exclusively breastfeeding
mothers being slightly older than their mixed feeding counterparts. Years of
formal education were
comparable between the two groups of mothers. Most of the mothers in both
groups were married, white/Caucasian, and either employed full time or part time.
Mean gestation age was 39.39±0.87 (37–41) weeks, with
no statistical difference in gestational age between the exclusively
breastfeeding mothers and mixed feeding mothers and also by gender of the child
(Table 1). There were no significant differences in both maternal and infant
parameters between the two groups except for maternal prepregnancy weight, prepregnancy
BMI, and maternal weight at delivery. Mothers of infants who received mixed
feeding reported higher prepregnancy weight (P=.034), prepregnancy BMI (P=.011),
and also weighed more at delivery (P=.033) than mothers of exclusively
breastfeeding infants (Table 1). The infants were identical in birth weight and
birth length in addition to gestational age. The mean birth weight was 3.47±0.42 (range 2.51–4.26) kilograms,
while mean birth length was 51.36±2.06 (of range 46.99–54.61)
centimeters. There were no significant differences in birth weight and birth
length between exclusively breastfeeding and mixed feeding infants.Table 1
Characteristics of mothers and infants according to
type of feeding.
Maternal characteristicsEBF (n=27)MF (n=13)P-valueAge (years)30.78±5.1628.23±4.48NSYears of schooling17.44±2.2617.31±3.30NSMaternal height (m)1.64±0.071.61±0.06NSMaternal prepregnancy weight (kg)59.90±8.2867.27±12.86.034Prepregnancy BMI (kg/m2)22.21±2.7726.15±6.59.011Maternal weight at delivery (kg)75.13±9.6882.66±10.91.033Pregnancy weight gain (kg)15.10±3.9515.42±4.52NSGestational age at delivery (weeks)39.46±0.8639.25±0.90NSn (%)n (%)Marital StatusNSMarried25 (92.6)11 (84.6)Single2 (7.4)2 (15.4)EthnicityNSWhite/Caucasian24 (88.9)10 (76.9)Black/African American3 (11.1)3 (23.1)Employment statusNSFull time15 (55.6)8 (61.5)Part time7 (25.9)4 (30.8)Not working5 (18.5)1 (7.7)Type of deliveryNSVaginal/spontaneous23 (85.2)8 (69.2)Cesarean4 (14.8)4 (30.8)Infant characteristicsBirth weight (kg)3.44±0.423.52±4.33NSBirth length (cm)51.36±2.0351.34±2.20NSGenderNSBoys15 (55.6)7 (53.8)Girls12 (44.4)6 (46.2)EBF: exclusive breasfeeding; MF: mixed feeding.Vaginal/spontaneous delivery was higher among exclusively breastfeeding infants
with cesarean delivery being higher among mixed feeding infants, although the
differences were not statistically significant (Table1).


## 3.2. Type of Feeding and Early Growth of Infant

There was a modest increase in body
weight across the feeding groups with time. Exclusively breastfeeding infants
tended to gain slightly more weight with time compared to mixed feeding
infants, although the differences in weight gain across time were not statistically
significant (Figure1). As depicted in Figure 1, the difference in weight gain
between the two groups became more prominent at 8 (117.7 grams) and 12 (81.6
grams) weeks postpartum compared to the difference at 2 (16.9 grams) and 4
(12.7 grams) weeks postpartum with respect to birth weight. A similar trend was
seen for infant length with exclusively breastfeeding infants gaining more
length than mixed feeding infants even though the difference was not
significant (data not shown).Figure 1
Changes in infant body weight with respect to
birth weight (EBF: exclusive breastfeeding; MF: mixed
feeding).


## 3.3. Type of Feeding and Early Infant Body Composition

The results from this study showed
gradual increase in the body composition (fat mass, fat-free mass, fat mass
index [FMI], and fat-free mass index [FFMI]) of infants with time. There were,
however, some differences in the accumulation of fat mass and fat-free mass. Exclusively
breastfeeding infants accumulated more fat mass compared to their mixed feeding
counterparts, whereas mixed feeding infants gained more fat-free mass compared
to exclusively breastfeeding infants, although the difference was not
statistically significant (data not shown). As shown in Figure2, both groups
started with about the same value for FMI at 2 weeks postpartum but with time
the data showed slight differences although these were not statistically
significant. Further examination of the data showed that exclusively
breastfeeding infants gained slightly more FMI at 4 (0.93 kg/m2 versus
0.84 kg/m2), 8 (1.92 kg/m2 versus 1.68 kg/m2),
and 12 (2.34 kg/m2 versus 2.10 kg/m2) weeks postpartum
with respect to their FMI as computed at 2 weeks postpartum compared to mixed
feeding infants (Figure 2). The results, therefore, show that by 12 weeks postpartum, infants
who are exclusively breastfeeding have a mean FMI which is at least 0.2 unit higher than infants
who are mixed feeding which is also an indication of higher adiposity among
exclusively breastfeeding infants compared to mixed feeding infants. For FFMI
which is a measure of infant lean mass, Figure 3 shows that unlike adiposity
mixed feeding infants tended to have higher amounts of lean mass at 2 weeks
postpartum and throughout the 12 weeks of follow-up compared to the exclusive
breastfeeding counterparts. Mean FFMI gains were 0.13 kg/m2 versus 0.12 kg/m2,
0.51 kg/m2 versus 0.65 kg/m2, and 0.39 kg/m2 versus
0.60 kg/m2 at 4, 8, and 12 weeks postpartum with respect to FFMI at
2 weeks postpartum for exclusively breastfeeding and mixed feeding infants,
respectively.Figure 2
Pattern of infant adiposity with time (EBF: exclusive breastfeeding; MF: mixed
feeding).Figure 3
Pattern of infant lean mass with time (EBF: exclusive breastfeeding; MF: mixed
feeding).The repeated measures analysis did not show any significance between group differences in
infant weight, length, fat mass, fat-free mass, FMI, FFMI, and percent body fat.
Adjusted for birthweight, birth length and infant gender, fat mass, fat-free
mass, FMI, and FFMI did not differ significantly between exclusively
breastfeeding and mixed feeding infants at 2, 4, 8, and 12 weeks postpartum.
There was a strong correlation between the computed FMI and the measured percent
body fat (r=0.949 to 0.974; P<.001) at each time point.


## 4. Discussion

The results from this pilot
prospective study suggest that exclusive breastfeeding may promote increased
weight gain and FMI in the early postpartum period (first 12 weeks after
delivery) compared to the mixed feeding. Although the results of infant body
composition measurement from this pilot studyare similar
to previously reported data by Fomon et al. [21], Butte et al. [22], and Gilchrist [23], slight differences in infant
feeding practices and infant growth and body composition are seen as they
compared exclusive breastfeeding and formula feeding with the current study
comparing exclusive breastfeeding to mix feeding. In agreement with the study
by Gilchrist [23], no significant gender
differences in weight gain and increase in adiposity were observed in this study, irrespective
of the feeding type during the early postpartum weeks. This finding contradicts
the findings by Buyken et al. [24] who studied older children. Buyken
et al. found that male children exclusively breastfed for longer duration were
protected against overweight/obesity even when their mothers were overweight [24]. In the study by Butte et al. [22], the authors observed higher
weight velocity in formula fed than breastfed infants age 3 to 6 months, which
is opposite to the findings from the current study of infants 0 to 12 weeks. Findings
from the current study show that weight gain of exclusively breastfed infants
was higher compared to their counterparts who received mixed feeding through
the first 12 weeks after delivery (Figure 1), which is in agreement with
previous studies, although they compared exclusive breastfeeding to formula
feeding [25–27].
This means infants who are exclusively breastfed experience rapid weight gain
during the first 12 weeks postpartum than infants who are either mixed or
artificially fed. This is an interesting finding
which needs further investigation beyond 12 weeks postpartum as we encourage
more mothers to exclusively breastfeed their newborn for the first 6 months
after delivery.Also, the percent body fat in the
exclusively breastfed infants exceeded that of mixed fed infants by 0.52% at 4
weeks postpartum, and the difference continued to increase throughout the study period, reaching 1.12% body fat at
12 weeks postpartum. The pattern of percent body fat gain observed in the
present study is consistent with the findings by Gilchrist [23]. The same pattern was
observed when FMI was used to assess infant adiposity (Figure 2). The
difference in FMI and percent body fat between the feeding groups, although not
statistically significant, is an important observation as it is a measure of
adiposity. With the strong association of high adiposity with cardiovascular
and other chronic diseases, it is important to understand why infants who are
exclusively breastfed gain more percent body fat than those who do not receive
exclusive breastfeeding in the first 12 weeks after delivery. It is also very
important for future studies to document what happens to the differences in
adiposity as infants double and triple their birthweight at 4–6 months and 9–12 months,
respectively. In the present study, there was no direct measure of the infants'
actual intake even though mothers who were mixed feeding reported proportion of
daily feeds that came from nonbreastmilk substitute. It will be interesting and
important for future studies to quantitatively estimate feed intake (breastmilk
only versus breastmilk, and formula versus formula only) and their respective
energy content to verify whether exclusively breastfeeding infants have higher
intakes than the other feeding groups during early postpartum leading to the
rapid weight and FMI/percent body fat gains. It will also be important to
understand the metabolism of infants receiving different feedings during the early
postpartum period. A better knowledge of the actual food intake and metabolic
rate during the early postpartum period will help to explain why exclusively breastfeeding infants
gain more body weight and FMI as well as percent body fat than infants
receiving mixed or artificial feeding within the first 3 months of life. This
information will also help in understanding why exclusive breastfeeding seems
to promote rapid weight gain and high adiposity in the early postpartum period,
while other studies find a protective effect or no effect on overweight/obesity
later in the child's life.Using the body mass index (BMI) as a
proxy for assessing obesity and adiposity, a number of studies have reported
the protective effect of breastfeeding on childhood obesity [28, 29]. These studies have been
cross-sectional in nature and have relied on maternal/caretaker recall on
infant feeding practices. Studies that have been prospective in nature in this
area have either reported no effect of breastfeeding on overweight/obesity [30] or breastfeeding as a risk
factor for overweight/obesity [31], while studies that employed
meta-analysis have reported slight to moderate protection of breastfeeding
against overweight/obesity during childhood [3, 5, 12, 17].
All these studies assessed the relationship between breastfeeding and
overweight/obesity among older children and not the early postpartum period. Although,
BMI tends to be a good screening tool for overweight/obesity, it is not enough,
particularly when assessing adiposity hence the contribution of the current
study using FMI in this area of research in the early postpartum period. By
using FMI, fat mass was adjusted by infant length which is a fat-free proxy and
not directly associated with body weight. Besides the weight and body
composition measurements in this area of research, the definition of
breastfeeding and duration may play important roles in the inconsistencies
reported in the literature. Even though the current study has a small sample
size, it is prospective in design. It applied the strictest definition for
exclusive breastfeeding and also employed the PEA POD body composition system
which has been proven to be accurate in the measurement of body composition in
infants [20]. There is, therefore, a need
for a prospective study with adequate power following children from early
infancy through at least adolescence using well-defined breastfeeding
definitions and dietary intake measures as well as using weight, BMI, and body
composition methodologies
that is proven to be accurate.Findings from the current study
alongside others suggest rapid weight gain and accumulation of adipose tissue
in the early postpartum period which require further examination of the actual
intake and metabolism of the infant to guide feeding and infant care recommendations
given to mothers and caregivers as a means of preventing overweight and
adiposity in children. It is important to emphasize that the study was designed
to compare exclusive breastfeeding and formula feeding infants and weight and
percent body fat accumulation, but the findings compare exclusive breastfeeding
and mixed feeding instead. The results from this study need to be interpreted
and generalized with caution because of the small sample and the participants
being mainly whites and well educated. This study is one of the few that has
examined the association between breastfeeding and childhood overweight/obesity
by actually measuring infant body composition in the early postpartum period.
With this said, practitioners and parents/caregivers should not lose sight of
the numerous health benefits of breastfeeding to the infant, mother, and the
entire society even during the early postpartum period. Also, the longer-term
consequences of breastfeeding on body composition have a greater public health
relevance than the effect within the first 12 weeks postpartum, requiring
further prospective studies.


## 5. Conclusion

The rate of both weight gain and
adiposity was slightly higher among infants who were exclusively breastfeeding
compared to their counterparts who received mixed feeding in the first 12 weeks
after delivery. Overall, exclusively breastfeeding infants had percent body fat
which was 1.3% higher than mixed feeding infants at 12 weeks postpartum. Exclusively
breastfeeding infants also weighed slightly more and had slightly higher FMI,
less FFMI at 12 weeks postpartum compared to their mixed feeding counterparts. There
is, therefore, a need for further prospective studies in this area to examine
what happens to the percent body fat at 6 months and 12 months postpartum as
infants are expected to double and triple their birth weight, respectively, as
6 months and 12 months postpartum are also high energy demand periods in the
infant's life. This, if addressed, will contribute to the search for effective
ways of overweight/obesity prevention especially in children. It will also give
a better understanding of the differences in adiposity between exclusively
breastfeeding, mixed feeding, and formula feeding infants in the early
postpartum period.



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*Source: 648091-2009-03-12.xml*