Association of biological, socioeconomic, and environmental factors with child development at two years of age in Bangladesh, Pakistan, and Tanzania: results from the AMANHI-ACT study

Background: The first 1,000 days of life, spanning pregnancy to two years, are critical for development. We investigated the association of maternal, socioeconomic, environmental, nutritional, and childhood characteristics with cognitive, motor, and language development at two years of age. Methods: The AMANHI-ACT study enrolled pregnant women between 8 and 19 weeks of gestation from Bangladesh, Pakistan, and Tanzania. Data was collected on sociodemographic factors, maternal BMI and co-morbidities during pregnancy, and weight and gestational age at birth. Child characteristics included vaccination history, infections, and physical growth at predefined intervals up to two years. Child development at two years was assessed using the Bayley Scales of Infant and Toddler Development Third Edition (Bayley-III). The home environment was assessed using the Home Observation for Measurement of the Environment Infant-Toddler (HOME-IT) tool. We performed linear regression and reported site-adjusted regression coefficients with 95% confidence intervals. Results: We assessed 3,062 children at two years of age to identify factors associated with their cognitive, language, and motor development scores. Cognitive scores were significantly lower among children whose mothers had no formal education (Adjusted coefficient = -3.8; 95% CI: -5.8, -1.8) and those who had not received any vaccinations (Adjusted coefficient = -6.0; 95% CI: -9.3, -2.6). Language development was similarly affected: children with mothers who had no education (Adjusted coefficient = -4.7; 95% CI: -6.8, -2.5) or only primary-level education (Adjusted coefficient = -4.5; 95% CI: -6.5, -2.5) showed markedly lower scores. Language scores were also reduced in children whose fathers had no education (Adjusted coefficient = -2.4; 95% CI: -4.2, -0.5) or only primary education (Adjusted coefficient = -2.4; 95% CI: -4.1, -0.6). For motor development, children who were stunted (Adjusted coefficient = -2.2; 95% CI: -2.9, -1.4), wasted (Adjusted coefficient = -2.8; 95% CI: -4.3, -1.4), or unvaccinated (Adjusted coefficient = -4.7; 95% CI: -8.0, -1.4) at two years exhibited significantly lower scores. Conclusion: Preterm births, vaccination history, parental education, and physical growth significantly affected the first 1000 days of child development, thus identifying areas for targeted intervention to optimize long-term health outcomes in LMICs.