Disentangling basal and accrued height‐for‐age for cross‐population comparisons

Abstract

Objectives: Current standards for comparing stunting across human populations assume a universal model of child growth. Such comparisons ignore population differences that are independent of deprivation and health outcomes. This article partitions variation in height-for-age that is specifically associated with deprivation and health outcomes to provide a basis for cross-population comparisons.Materials and Methods: Using a multilevel model with a sigmoid relationship of resources and growth, we partition variation in height-for-age z-scores (HAZ) from 1.5 million children across 70 countries into two components: (1) "accrued HAZ" shaped by environmental inputs (e.g., undernutrition, infectious disease, inadequate sanitation, poverty) and (2) a country-specific "basal HAZ" independent of such inputs. We validate these components against population-level infant mortality rates and assess how these basal differences may affect cross-population comparisons of stunting.Results: Basal HAZ differs reliably across countries (range of approximately 1.5 SD) and is independent of measures of infant mortality. By contrast, accrued HAZ captures stunting as impaired growth due to deprivation and is more closely associated with infant mortality than observed HAZ. Assessing stunting prevalence by accrued HAZ suggest that populations in West Africa and Haiti suffer much greater levels of stunting than indicated by observed HAZ.Discussion: Current universal standards may dramatically underestimate stunting in populations with taller basal HAZ. Relying on observed HAZ rather than accrued HAZ may also lead to inappropriate cross-population comparisons, such as concluding that Haitian children enjoy better conditions for growth than do Indian or Guatemalan children.

Why Are Indian Children So Short? The Role of Birth Order and Son Preference

“…At the prenatal stage, both mechanisms benefit daughters without an older brother: there is no sibling rivalry and parents will invest in her while she is in utero anticipating that, with 50 percent chance, they are investing in their eldest son. 24 Post-birth, the negative effects of son-biased fertility-stopping behavior materialize as parents reoptimize fertility and expenditure decisions. Thus, at the postnatal stage, not having an older brother disadvantages girls through the fertility continuation mechanism.…”

An Agricultural Wealth Index for Multidimensional Wealth Assessments

“…We focused on women aged 40–49 as they normally show maximal associations between BMI and wealth (Hruschka, Hackman, and Stulp 2019; Hruschka, Hadley, and Brewis 2014; Hruschka and Hadley 2016). For child growth outcomes, we focused on 12–59‐month‐old children as prior research has shown HAZ may not be a particularly reliable measure of nutrition among 0–11 month olds (Hackman and Hruschka 2020; Wright 2000). Adult BMI was calculated as weight (kg)/height (m) 2 , and we excluded cases with values below 10 or above 80.…”

One size does not fit all. How universal standards for normal height can hide deprivation and create false paradoxes

“…Child A enjoyed adequate nutrition and low disease burden and reached her maximum potential height. By contrast, Child B had a genetic potential to grow much taller than child A in an optimal environment, but was chronically undernourished and subjected to substantial disease burden (Hackman & Hruschka, 2020). A one‐size‐fits‐all cutoff for height would make these two children look equally healthy, despite drastic differences in their environments and mortality risks.…”

“…Haiti's infant mortality rate is 50% greater and its GDP per capita is less than a third of India's. Yet, by the WHO growth standards, Haitian children seem to be doing much better than Indian children, with only 6% of Haiti's children classified as severely stunted compared to 14% in India (Hackman & Hruschka, 2020).…”

“…Some factors such as open defecation can account for a small portion of the difference, while other flawed analyses claim to account for up to 50% of the gap (Hruschka & Hackman, 2020). However, none of these explanations has yet to fully account for the enigma (Hackman & Hruschka, 2020).…”