Biological and environmental correlates of infant neurodevelopment at six months: an exploratory regression analysis

Early neurodevelopment results from the interaction between biological conditions at birth and the postnatal caregiving environment. Understanding the relative contribution of these factors during early infancy may improve early identification of children at developmental risk. To examine associations between biological, maternal, and environmental factors and neurodevelopmental outcomes at six months of age. A cross-sectional study was conducted among 124 healthy term infants aged six months. Neurodevelopment was assessed using the Ages and Stages Questionnaire, Third Edition (ASQ-3) across five developmental domains: communication, gross motor, fine motor, problem solving, and personal–social development. Potential predictors were categorized as biological factors (sex, birth weight, gestational age, breastfeeding status, and prenatal alcohol exposure), maternal factors (maternal educational attainment and early postpartum return to employment), and environmental factors (primary language spoken in the home and daily parent–infant verbal interaction). Hierarchical multiple regression analyses were performed to evaluate the independent contribution of each predictor group to infant neurodevelopmental outcomes. Biological variables showed the most consistent associations across models, although the proportion of explained variance was modest. Birth weight emerged as the most stable predictor, showing significant positive associations with communication, gross motor, problem-solving, and personal–social development. Prenatal alcohol exposure was associated with lower personal–social scores. Sex differences were observed in communication outcomes, with female infants demonstrating slightly higher scores. Maternal and environmental factors contributed only modestly to explained variance and were not retained as independent predictors in the final regression models. In this exploratory cross-sectional study of healthy term infants, biological variables, particularly birth weight, showed the most consistent associations with developmental scores at six months. Prenatal alcohol exposure was associated with lower personal–social scores. However, the explained variance was modest, and findings should be interpreted cautiously given the sample size, imbalance in some predictors, and the cross-sectional design.