Height in healthy children in low- and middle-income countries: an assessment

Background: Despite rapid economic development and reductions in child mortality worldwide, continued high rates of early childhood stunting have put the global applicability of international child-height standards into question. Objectives: We used population-based survey data to identify children growing up in healthy environments in low-and middle-income countries and compared the height distribution of these children to the height distribution of the reference sample established by the WHO. Design: Height data were extracted from 169 Demographic and Health Surveys (DHSs) that were collected across 63 countries between 1990 and 2014. Children were classified as having grown up in ideal environments if they 1) had access to safe water and sanitation; 2) lived in households with finished floors, a television, and a car; 3) were born to highly educated mothers; 4) were single births; and 5) were delivered in hospitals. We compared the heights of children in ideal environments with those in the WHO reference sample. Results: A total of 878,249 height records were extracted, and 1006 children (0.1%) were classified as having been raised in an ideal home environment. The mean height-for-age z score (HAZ) in this sample was not statistically different from zero (95% CI: -0.039, 0.125). The HAZ SD for the sample was estimated to be 1.3, and 5.3% of children in the sample were classified as being stunted (HAZ <-2). Similar means, SDs, and stunting rates were found when less restrictive definitions of ideal environments were used. Conclusion: The large current gaps in children's heights relative to those of the reference sample likely are not due to innate or genetic differences between children but, rather, reflect children's continued exposure to poverty, a lack of maternal education, and a lack of access to safe water and sanitation across populations.