Prenatal Maternal Immune Activation Predicts Observed Fearfulness in Infancy

Fear reactivity is an early emerging temperament trait that predicts longer term behavioral and health outcomes. The current analysis tests the hypothesis, an extension of prior research on maternal immune activation (MIA), that the prenatal maternal immune system is a reliable predictor of observed fear reactivity in infancy. The analysis is based on a prospective longitudinal cohort study that collected data from the first trimester and conducted observational assessments of temperament at approximately 12 months of age (n = 281 infants). MIA was assessed from immune biomarkers measured in maternal blood at each trimester; infant temperament was assessed using the Laboratory Temperament Assessment Battery assessment at 12 months; covariates included family and sociodemographic factors. Patterns of inflammatory markers across gestation reliably predicted observed temperament: elevated prenatal MIA was associated with high fear reactivity to novel stimuli. The findings provide novel evidence of prenatal origins of fear reactivity and suggest developmental mechanisms that may underlie early emerging individual differences in child temperament. Public Significance StatementThis research examines the prenatal developmental origins of a key aspect of child behavioral development, fear reactivity in infancy. The findings provide the first robust evidence that maternal immune activation in pregnancy is associated with early-emerging fear reactivity. These results extend prior work on prenatal influence on child behavioral development in ways that suggest developmental mechanisms and potential intervention targets for promoting child health and behavioral and social development.