Predictors of motor developmental milestones during the first year of life.

UNLABELLED: Studies suggest that both pre- and postnatal factors are predictors of age of attaining milestones in infancy. However, no studies evaluate the comparative strength of these predictors and the amount of the variance in development they explain. This study aimed to conduct a systematic evaluation of a broad selection of possible predictors of age at milestone attainment and to identify factors that explain significant inter-individual variance. Mothers of 5765 children of the Copenhagen Perinatal Cohort (1959-61) recorded 12 developmental milestones prospectively during the child's first year of life. Information on possible predictors was collected during pregnancy and at follow-up and was categorized into the domains: Family background, Pregnancy and delivery, Postnatal influences, and Postnatal growth. The domain Pregnancy and delivery contributed most of the explained variance in Overall mean of milestones (14.4%), with especially gestational age (β = -0.15; p ≤ 0.001) and birth weight (β = -0.16; p ≤ 0.001) being important predictors.

CONCLUSION: Several individual factors, especially gestational age, birth weight, breastfeeding, having lived in a full-time institution, and weight and head increase in the first year, were significantly associated with milestone attainment in the first year of life. Variables within the domain of Pregnancy and delivery explained the largest proportion of variance in milestone attainment compared to the other domains. What is known: • Younger age at attainment of motor developmental milestones positively predicts cognitive outcomes in adulthood. • Both pre- and postnatal factors have been associated with age of attaining milestones in infancy. What is new: • First study to provide a systematic evaluation of a broad selection of predictors of infant milestone attainment. • Variables within the domain of Pregnancy and delivery, especially gestational age and birth weight, explained the largest proportion of variance in milestone attainment. • The variance explained by the predictors decreased time-dependently with later milestones.