Prenatal prolactin predicts postnatal parenting attitudes and brain structure remodeling in first-time fathers.

Despite the important contributions that fathers make to parenting, the neurobiological underpinnings of men's adaptation to parenthood are still not well understood. The current study focuses on prolactin, a hormone that has been extensively linked with reproduction, lactation, and parental behavior in mothers. There is preliminary evidence that prolactin may also reflect the transition to sensitive fatherhood. We sampled prolactin in 91 first-time expectant fathers who participated in a laboratory visit along with their pregnant partners. Fathers' prolactin levels were correlated with their partners' prolactin levels. Men's prolactin levels during their partner's pregnancy were associated with their self-reported antenatal bonding to the unborn infant. Prenatal prolactin levels in fathers also predicted more positive attitudes toward fatherhood at three months postpartum, including lower parenting stress, greater enjoyment of the infant, and a more attunement-oriented parenting style. Within a smaller sample of 32 men who participated in MRI scanning before and after their child's birth, prenatal prolactin also predicted greater reductions in grey matter volume in the left posterior cingulate, left insula, and left nucleus accumbens. In conclusion, men's prenatal prolactin may reflect their perceptions of fatherhood and changes to their perinatal brain structure.