(OR38-04-24) Are Boys More Vulnerable to Stunting? Examining Risk Factors, Differential Sensitivity, and Measurement Issues in Zambian Infants and Young Children

Objectives: Stunting remains a considerable public health problem globally, and sex differences in prevalence have been documented. While many risk factors for stunting have been identified, few studies examine how these factors may contribute to sex differences. We test whether: 1) boys and girls are differentially exposed to stunting risk factors, 2) boys and girls respond differently to similar exposures, and 3) these associations are sensitive to the growth measures used.

Methods: Data come from 7486 Zambian infants and young children, aged 0-24 months, participating in the SUN (Scaling Up Nutrition) 2.0 Program baseline survey. Surveys and dietary recalls were collected from primary caregivers, and anthropometry was collected for caregivers and children. Stunting was defined as height-for-age z-score (HAZ) < -2 (WHO). Descriptive statistics and adjusted multilevel logistic regression models controlling for age and province were used to identify sex differences in exposures and risk factors for stunting, respectively. Interaction terms between exposure and infant sex were added to test for sex differences in response. Sensitivity testing with alternate measures of infant size, including height-for-age difference (HAD), was conducted.

Results: Boys were more likely to be stunted than girls (34.5% vs 25.7%, respectively). Numerous maternal, care giving, diet, and household characteristics were associated with the risk of stunting, but few sex differences were seen in exposure to these factors. A limited number of risk factors showed evidence for moderation by sex at the p< 0.10 level and only one, maternal marital status, at p< 0.05. Boys were longer than girls at all ages and no sex differences were seen in the patterns of HAZ or HAD with age. Results were robust to alternate specifications.

Conclusions: Our results show that boys have lower mean HAZ scores than girls and a greater prevalence of stunting during the first two years of life. We do not find strong evidence that feeding practices, environmental exposures, or care giving differ consistently between boys and girls or that boys and girls respond differently to these exposures. Our results indicate that further investigation of prenatal factors and/or the performance of growth standards by sex is needed.

Funding Sources: This research is funded by USAID.