Respiratory sinus arrhythmia moderates the impact of maternal prenatal anxiety on infant negative affectivity.

Maternal prenatal anxiety is associated with infants' temperamental negative affectivity (NA), but it is unclear to what extent children vary in their susceptibility to prenatal influences. We tested a hypothesis that infants' respiratory sinus arrhythmia (RSA), an index of parasympathetic vagal tone and a potential marker of differential susceptibility to environmental influences, moderates the effects of maternal prenatal anxiety on the development of infant NA. Prenatal anxiety was assessed during the last trimester of pregnancy in a low-risk community sample. Infant NA, baseline RSA, and maternal postnatal anxiety were assessed at 8-10 months of infant age. Regression analyses were performed to predict infant NA on the basis of prenatal anxiety, infant baseline RSA, and their interaction (N = 173). Maternal prenatal anxiety and infant RSA interactively predicted infant NA at 8-10 months. Among infants with high RSA, a significant positive association between prenatal anxiety and infant NA was observed, whereas prenatal anxiety did not predict infant NA among infants with low RSA. Vagal tone, as indexed by baseline RSA, may provide a promising marker of differential susceptibility to the long-term effects of varying intrauterine conditions.