Interparental relationship dynamics and cardiac vagal functioning in infancy.

This study examined associations between interparental relationship dynamics and vagus system functioning in infancy. The functioning of the vagus system, part of the parasympathetic nervous system, indexes emotional reactivity and regulation. Interparental avoidance and dyadic adjustment constitute the focus of this study in order to bring attention to relationship dynamics not subsumed under overt conflict. Infants' baseline vagal tone and change in vagal tone in response to a novel toy were assessed at 5 months in a sample of high-risk mother-infant dyads (n=77). Maternal report of interparental avoidance demonstrated an association with infants' baseline vagal tone, while interparental dyadic adjustment was associated with change in infants' vagal tone from baseline to the novel toy. Infant gender moderated these associations. Maternal sensitivity did not mediate interparental relationship dynamics and infants' vagal functioning. Results are discussed in the context of emotional security theory.