Height-for-age z scores increase despite increasing height deficits among children in 5 developing countries

Abstract

Background: Growth failure remains a persistent challenge in many countries, and understanding child growth patterns is critical to the development of appropriate interventions and their evaluation. The interpretation of changes in mean height-for-age z scores (HAZs) over time to define catch-up growth has been a subject of debate. Most studies of child growth have been cross-sectional or have focused on children through age 5 y.

Objective: The aim was to characterize patterns of linear growth among individuals followed from birth into adulthood.

Design: We compared HAZs and difference in height (cm) from the WHO reference median at birth, 12 mo, 24 mo, mid-childhood, and adulthood for 5287 individuals from birth cohorts in Brazil, Guatemala, India, the Philippines, and South Africa.

Results: Mean HAZs were <0 at birth in the 3 cohorts with data and ranged from -0.6 (Brazil) to -2.9 (Guatemala) at age 24 mo. Between 24 mo and mid-childhood, HAZ values increased by 0.3-0.5 in South Africa, Guatemala, and the Philippines and were unchanged in Brazil and India. Between mid-childhood and adulthood, mean HAZs increased in all cohorts but remained <0 in adulthood [mean range: -0.3 (Brazil) to -1.8 (Guatemala and Philippines)]. However, from 24 mo to adulthood, height differences from the reference median became greater.

Conclusions: From age 2 y to adulthood, mean HAZs increased, even though height deficits relative to the reference median also increased. These 2 metrics may result in different interpretations of the potential for and the impact of catch-up growth in height.

FIGURE 1.

Prevalence of stunting among children in 5 birth cohorts in middle-income countries: Consortium of Health-orientated Research in Transitioning Societies. Stunting is defined as height-for-age z score <−2.0. Mid-C, mid-childhood.

FIGURE 2.

Incidence of stunting among children in 5 birth cohorts in middle-income countries: Consortium of Health-orientated Research in Transitioning Societies. The incidence of stunting is the proportion of children who were not stunted at an earlier survey round but who were stunted at a later survey round (stunting is defined as height-for-age z score <−2.0). *Height data at birth were not available for Brazil and South Africa. Mid-C, mid-childhood.

FIGURE 3.

Incidence of recovery among children in 5 birth cohorts in middle-income countries: Consortium of Health-orientated Research in Transitioning Societies. The incidence of recovery is the proportion of children who were stunted at an earlier survey round but who were not stunted at a later survey round (stunting is defined as height-for-age z score <−2.0). *Height data at birth were not available for Brazil and South Africa; the incidence of recovery was 0.0% in Guatemala. Mid-C, mid-childhood.