Research Article: Childhood stunting in relation to the pre- and postnatal environment during the first 2 years of life: The MAL-ED longitudinal birth cohort study

Date Published: October 25, 2017

Publisher: Public Library of Science

Author(s): Lars Åke Persson

Abstract: BackgroundStunting is the most prevalent manifestation of childhood malnutrition. To characterize factors that contribute to stunting in resource-poor settings, we studied a priori selected biological and social factors collected longitudinally in a cohort of newborns.Methods and findingsWe enrolled 1,868 children across 7 resource-poor settings in Bangladesh, Brazil, India, Nepal, Peru, South Africa, and Tanzania shortly after birth and followed them for 24 months between 2 November 2009 and 28 February 2014. We collected longitudinal anthropometry, sociodemographic factors, maternal-reported illnesses, and antibiotic use; child feeding practices; dietary intake starting at 9 months; and longitudinal blood, urine, and stool samples to investigate non-diarrheal enteropathogens, micronutrients, gut inflammation and permeability, and systemic inflammation. We categorized length-for-age Z-scores into 3 groups (not stunted, ≥−1; at risk, <−1 to −2; and stunted, <−2), and used multivariable ordinal logistic regression to model the cumulative odds of being in a lower length-for-age category (at risk or stunted). A total of 1,197 children with complete longitudinal data were available for analysis. The prevalence of having a length-for-age Z-score below −1 increased from 43% (range 37%–47% across sites) shortly after birth (mean 7.7 days post-delivery, range 0 to 17 days) to 74% (16%–96%) at 24 months. The prevalence of stunting increased 3-fold during this same time period. Factors that contributed to the odds of being in a lower length-for-age category at 24 months were lower enrollment weight-for-age (interquartile cumulative odds ratio = 1.82, 95% CI 1.49–2.23), shorter maternal height (2.38, 1.89–3.01), higher number of enteropathogens in non-diarrheal stools (1.36, 1.07–1.73), lower socioeconomic status (1.75, 1.20–2.55), and lower percent of energy from protein (1.39, 1.13–1.72). Site-specific analyses suggest that reported associations were similar across settings. While loss to follow-up and missing data are inevitable, some study sites had greater loss to follow-up and more missing data than others, which may limit the generalizability of the findings.ConclusionsNeonatal and maternal factors were early determinants of lower length-for-age, and their contribution remained important throughout the first 24 months of life, whereas the average number of enteropathogens in non-diarrheal stools, socioeconomic status, and dietary intake became increasingly important contributors by 24 months relative to neonatal and maternal factors.

Partial Text: Stunting is the most prevalent condition of child malnutrition worldwide [1], and it is associated with negative health and economic outcomes later in life, including shorter adult height, less schooling, and reduced adult income [2]. An estimated 165 million children younger than 5 years old are stunted [1], and 90% of these children live in 36 countries, mostly in Asia and Africa [3]. Stunting typically begins in utero and usually reflects persistent, cumulative effects of poor nutrition and other deficits that often span across several generations [4,5]. Determinants of stunting may be affected by distal factors, such as geopolitics and economics, and proximal factors, such as inadequate diet and endemic disease [1]. Analyses of the World Health Organization Global Database on Child Growth and Malnutrition found that length-for-age starts close to the standard but falters dramatically in the first 2 years of life consistently across Asia, Africa, and Latin America, and this trend appears to have remained unchanged for decades [6,7]. Therefore, a comprehensive characterization of what occurs during this critical period, when substantial brain and cognitive function are also developing, is an urgent global priority. Potential contributors to growth shortfalls such as enteric infections and food intake warrant careful study to identify potentially effective interventions. It is precisely a better understanding of these risk factors in this critical formative window of early childhood that has been the focus of the MAL-ED (Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development) study, a multi-center study aimed at evaluating risk factors for growth faltering and associated health outcomes in children. Here we sought to evaluate how select neonatal, maternal, and postnatal factors, which represent different hierarchical levels depicted in the UNICEF malnutrition framework [1,8], contribute to low length-for-age in the first 2 years of life (Fig 1).

In the 7 resource-poor sites included in this analysis, children experienced length-for-age shortfalls relative to the WHO reference as they aged. Despite diverse cultures and geography, children at all sites (except Brazil) had linear growth faltering during childhood, with the prevalence of stunting reaching a plateau by 2 years, as per a previously reported observation [22]. Specifically, 74% of children were more than 1 SD below the WHO length standard by their second birthday, up from 43% at enrollment. Five factors contributed to being in a lower length-for-age category (at risk or stunted) during early childhood: lower enrollment weight, shorter maternal height, higher prevalence of enteropathogen detection, lower SES (WAMI index), and consumption of a lower percent of energy from protein in non-breast-milk foods. Neonatal and maternal factors were early determinants of childhood stunting, whereas 3 postnatal factors became increasingly important by 24 months.



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