Association of iron supplementation and deworming with early childhood development: analysis of Demographic and Health Surveys in ten low- and middle-income countries.

We assessed the associations of iron supplementation and deworming separately or combined with improved early childhood development (ECD) status. Cross-sectional data were analyzed for 29,729 children aged 36–59 months surveyed using the Demographic and Health Surveys in ten low- and middle-income countries, where iron supplementation and deworming are recommended by the World Health Organization. In each country, we estimated linear regression models for the effects of iron supplementation and deworming individually or combined on the Early Childhood Development Index (ECDI) z score, and whether this association differed between various ECD domains and the sex and residence of the child. Estimates were pooled using random-effects meta-analyses. Compared with receiving neither of the two interventions, iron supplementation plus deworming was associated with an increased ECDI z score (β = 0.13, 95% confidence interval (CI) 0.03–0.22, p = 0.009), particularly in rural residences. However, iron supplementation and deworming, individually, were not associated with the ECDI z score. Iron supplementation plus deworming was associated with higher odds of on-track development in literacy–numeracy (OR = 1.57, 95% CI 1.24–2.01, p < 0.001) and learning domains (OR = 1.27, 95% CI 1.09–1.48, p = 0.003), but not with development in the social–emotional and physical domains. Iron supplementation plus deworming, particularly for populations who are more susceptible to iron deficiency and intestinal worm infections, could be an important intervention for improving ECD. These findings may inform the argument for the necessity of implementing iron supplementation and deworming for preschool-age children.