Early-Life Conditions and Children’s Adaptive Behavior Scales at Age Three

This paper examines how early-life conditions are associated with children’s adaptive behavior at age three in the United Kingdom. We study two indicators of adverse perinatal health, low birth weight and preterm birth, alongside breastfeeding as an early postnatal investment. Using data on 4,335 chil dren from the Understanding Society Pregnancy and Early Childhood dataset observed between 2011 and 2023, the primary analysis combines weighted ordinary least squares with inverse-probability weighted regression adjustment; correlated random effects and within-sibling comparisons are used as complementary sensitivity analyses. Low birth weight and preterm birth are associated with lower adaptive behavior, with the largest gradients in the physical domain. Breastfeeding is more strongly associated with communication and socio-emotional functioning. In the preferred specification, the estimated associations are about 0.3 standard deviations for low birth weight, 0.2 to 0.25 standard deviations for preterm birth, and 0.1 to 0.15 standard deviations for breastfeeding. A supplementary pathway analysis using maternal engagement measured in a survey wave preceding the age-three out come provides suggestive evidence of a positive engagement component, especially for socio-emotional development; it is reported as a model-based rather than causal decomposition. These findings show how risks visible around birth map into functional differences relevant for screening, referral, and targeted family support in the preschool years.