Childhood height-for-age z-scores (HAZ) have been improving in many countries over the last few decades. Most HAZ faltering in malnourished populations takes place during the first 1000 days of life, in the prenatal period and the first two years after birth, but little is known about how growth faltering evolves over time in countries witnessing significant HAZ improvement. We aimed to quantify the evolution of population-level patterns of growth faltering using a novel analytic approach.
We selected 37 low and middle-income countries with at least two Demographic and Health Surveys 7+ years apart with statistically significant increases in HAZ among children 0-59m. For the first (T1) and second (T2) round for each country we use spline-based regressions to estimate monthly HAZ loss over the prenatal period (conception to 1m of age) and three postnatal periods (1-6m, 6-20m and 20m onwards). We tested for statistically significant changes in the speed of HAZ loss between T1 and T2. We report results by T1 HAZ, country, and region.
The fastest HAZ improvements between T1 and T2 occurred in Armenia, Ethiopia, Bangladesh, Nepal and India. South Asia had the fastest HAZ improvement of any major region. In South Asia and Eastern Africa, where baseline prenatal HAZ loss was prominent, the majority of HAZ improvement occurred in the prenatal period, suggesting progress in maternal factors. Improvements in regions with less baseline growth faltering typically stemmed from gains in postnatal HAZ, in the 1-6m or 6-24m period, but never the 24-59m period. Several countries in Central and Western Africa, where overall HAZ changes were modest, showed improvement in some age ranges but deterioration in others (e.g. Nigeria).
Conclusions : HAZ improvements between T1 and T2 stemmed from a mix of changes in prenatal and postnatal growth faltering, with substantial variability across countries. The timing and speed of HAZ changes varied markedly by country and region, and over time. Examining the patterns of growth faltering over time can yield important insights into the biological origins of population-level HAZ improvements and point to successes and failures of policy efforts to address the drivers of child growth, and the challenges for designing new and improved approaches.
Funding Sources :
Bill & Melinda Gates Foundation through ARENA, led by International Food Policy Research Institute, Wellcome Trust grant to Federal University of Pelotas.