Population-level linear growth faltering in low-income and middle-income countries
Authors: Jean H Humphrey, Andrew J Prendergast
Journal: The Lancet Global Health (2017)

Linear growth faltering or stunting among young children in low-income and middle-income countries remains a stubborn global health challenge. Postnatal stunting largely occurs between birth and 24 months of age when mean length-for-age Z score (LAZ) plummets from −0·5 to −2·0, with little change thereafter.1Victora CG De Onis M Hallal PC Blossner M Shrimpton R Worldwide timing of growth faltering: revisiting implications for interventions.Pediatrics. 2010; 125: e473-e480Crossref PubMed Scopus (889) Google Scholar Stunting influences all life stages, reducing survival in infancy,2Olofin I McDonald CM Ezzati M et al.Associations of suboptimal growth with all-cause and cause-specific mortality in children under five years: a pooled analysis of ten prospective studies.PLoS One. 2013; 8: e64636Crossref PubMed Scopus (272) Google Scholar educational attainment in childhood,3Maluccio JA Hoddinott J Behrman JR Martorell R Quisumbing AR Stein AD The impact of improving nutrition during early childhood on education among Guatemalan adults.Econ J. 2009; 119: 734-763Crossref Scopus (276) Google Scholar and economic productivity in adulthood.4McGovern ME Krishna A Aguayo VM Subramanian S A review of the evidence linking child stunting to economic outcomes.Int J Epidemiol. 2017; 46: 1171-1191Crossref PubMed Scopus (102) Google Scholar Moreover, offspring of adults who experienced linear growth faltering as children are at increased risk of stunting, creating an intergenerational cycle of reduced human capital. Globally, 23% (155 million) of all children younger than 5 years have a height-for-age Z score (HAZ) less than −2·0; these children are defined as stunted.5UNICEF/WHO/World Bank Joint Child Malnutrition Estimates Me.http://www.who.int/nutgrowthdb/jme_brochoure2017.pdf?ua=1Date: 2017Google Scholar The number and proportion of stunted children is widely tracked by governments and international agencies as a population indicator of child nutritional status and wellbeing. Specifically, WHO has resolved to reduce the number of stunted children in the world by 40% (from 165 million in 2012 to 100 million in 2025).6Onis M Dewey KG Borghi E et al.The World Health Organization's global target for reducing childhood stunting by 2025: rationale and proposed actions.Matern Child Nutr. 2013; 9: 6-26Crossref PubMed Scopus (207) Google Scholar In The Lancet Global Health, Daniel Roth and colleagues7Roth DE Krishna A Leung M Shi J Bassani DG Barros AJD Early childhood linear growth faltering in low-income and middle-income countries as a whole-population condition: analysis of 179 Demographic and Health Surveys from 64 countries (1993–2015).Lancet Glob Health. 2017; 5: e1249-e1257Summary Full Text Full Text PDF PubMed Scopus (53) Google Scholar present an analysis of growth data from children aged 0–36 months who participated in 179 Demographic and Health Surveys conducted in 64 low-income and middle-income countries. The authors show that the well recognised decline in mean HAZ between birth and 36 months is accompanied by declines in both the 5th and 95th percentiles, such that the entire HAZ distribution shifts downward. Their analysis establishes that the decline in population mean HAZ is not just due to an increase in the proportion of children who are stunted (ie, have a HAZ <–2) but also to stunting among all children across the entire HAZ distribution. They conclude that the primary underlying causes of stunting are ubiquitous factors affecting all children in low-income and middle-income countries that must be identified and addressed to solve the stunting problem. Roth and colleagues assert that childhood linear growth faltering has only occasionally been explicitly acknowledged as a whole-population condition. On the contrary, we find their comprehensive analysis to be consistent with the global perspective on stunting. While WHO has set global targets based on the proportion of stunted children (because binary outcomes are easier to communicate and interpret) they caution that "it is important to bear in mind that in reality there are not two distinct populations—one stunted and the other growing adequately—but rather a gradation of growth faltering".8Onis M Branca F Childhood stunting: a global perspective.Matern Child Nutr. 2016; 12: 12-26Crossref PubMed Scopus (533) Google Scholar The process of stunting is the clinical manifestation of underlying pathogenic processes that impair healthy development of the immune system, brain, and other organs. Indeed, the adverse effects of growth faltering on mortality, educational attainment, intelligence quotient, and adult employment occur in a near dose-response relationship to the degree of growth deficit across the HAZ distribution, rather than a sudden increase in risk once the HAZ falls below −2.2Olofin I McDonald CM Ezzati M et al.Associations of suboptimal growth with all-cause and cause-specific mortality in children under five years: a pooled analysis of ten prospective studies.PLoS One. 2013; 8: e64636Crossref PubMed Scopus (272) Google Scholar, 9Horta BL Victora CG de Mola CL et al.Associations of linear growth and relative weight gain in early life with human capital at 30 years of age.J Pediatr. 2017; 182 (e3.): 85-91Summary Full Text Full Text PDF PubMed Scopus (27) Google Scholar Additionally, although the magnitude of adverse effects are greatest for children with HAZ less than −2, there are far more children with higher HAZ who have, nonetheless, faltering growth. These stunting but not yet stunted children substantially contribute to economic and human capacity losses on a population level: Fink and colleagues10Fink G Peet E Danaei G et al.Schooling and wage income losses due to early-childhood growth faltering in developing countries: national, regional, and global estimates.Am J Clin Nutr. 2016; 104: 104-112Crossref PubMed Scopus (52) Google Scholar calculated the economic impact of shifting the entire HAZ distribution for children younger than 5 years in all low-income and middle-income countries to match the WHO reference population distribution; failure to do so currently costs the world at least $176·8 billion per annual birth cohort. Roth and colleagues recommend that stunting interventions should address population-level social and macroeconomic determinants of growth faltering. This is precisely what Brazil did between 1974 and 2007 when they operationalised political policies designed to narrow socioeconomic inequalities.11Monteiro CA Benicio MHDA Conde WL et al.Narrowing socioeconomic inequality in child stunting: the Brazilian experience, 1974–2007.Bull World Health Organ. 2010; 88: 305-311Crossref PubMed Scopus (170) Google Scholar These interventions not only reduced the proportion of stunted children from 37% to 7%, but sequentially shifted the entire HAZ distribution among children younger than 5 years (figure). Two-thirds of the stunting decline was attributable to increasing four factors: maternal education, family purchasing power, maternal and child health care, and public water supplies and sewage systems. Roth and colleagues suggest that stunting prevention should target the whole community, but stunting is concentrated in the most deprived and underserved subgroups within a country. In a modelling exercise, Carrera and colleagues12Carrera C Azrack A Begkoyian G et al.for the UNICEF Equity in Child SurvivalHealth and Nutrition Analysis TeamThe comparative cost-effectiveness of an equity-focused approach to child survival, health, and nutrition: a modelling approach.Lancet. 2012; 380: 1341-1351Summary Full Text Full Text PDF PubMed Scopus (63) Google Scholar demonstrated that targeting of the lowest economic strata or most marginalised part of the population is the most effective and cost-effective approach to reduce stunting, even though the whole population is affected. Empirically, this so-called equity approach was what resulted in the upward HAZ distribution shift in Brazil.11Monteiro CA Benicio MHDA Conde WL et al.Narrowing socioeconomic inequality in child stunting: the Brazilian experience, 1974–2007.Bull World Health Organ. 2010; 88: 305-311Crossref PubMed Scopus (170) Google Scholar The analysis by Roth and colleagues therefore confirms the current global perspective of stunting and highlights the gaps in our knowledge regarding mechanisms of growth failure. It is only once we better understand the process of stunting that we can devise more effective interventions that will benefit whole populations who currently bear the long-term sequelae of inadequate growth. We declare no competing interests. AJP is funded by the Wellcome Trust (108065/Z/15/Z); JHH is supported by a grant from the Bill & Melinda Gates Foundation (OPP1021542). Early childhood linear growth faltering in low-income and middle-income countries as a whole-population condition: analysis of 179 Demographic and Health Surveys from 64 countries (1993–2015)In low-income and middle-income countries, declines in mean HAZ with age are due to a downward shift in the entire HAZ distribution, revealing that children across the HAZ spectrum experience slower growth compared to the international standard. Efforts to mitigate postnatal linear growth faltering in low-income and middle-income countries should prioritise action on community-level determinants of childhood HAZ trajectories. Full-Text PDF Open Access