Birthweight moderates the association between chronological age and infants’ abilities to respond to cues for joint attention

Infants born preterm are more likely than ever to survive, but relatively little is known about the factors that influence their subsequent sociocognitive development. Responding to joint attention (RJA) is a pivotal skill that is likely supported by biological preparedness at birth and ex-utero social experience. The goals of this study are to evaluate the relative roles of chronological age, gestation duration, and birthweight for early RJA and examine birthweight as a potential moderator of the associations between chronological age and RJA. This study leveraged a mixed longitudinal design of infants (N = 256, obs = 421) from 8 to 16 months of chronological age. Results show that chronological age and gestation duration both explain unique variation in RJA. Further, birthweight exhibits quadratic relations with RJA. Birthweight moderates the association between chronological age and RJA; infants born heavier demonstrate faster RJA growth compared to those born smaller. Findings suggest that birth weight, an index of nutrient sufficiency in utero and biological preparedness, may constrain or afford early RJA development, consistent with the Developmental Origins of Health and Disease (DoHAD) hypothesis. Findings inform our understanding of the roles of biological preparedness and experience in shaping RJA and help disaggregate potential mechanisms of prematurity-related challenges to social cognitive development.