Left hippocampal volume across the transition to first-time fatherhood

• In Event: Parents develop, too: Maternal and Paternal Neural Reorganization Across the Perinatal Period

Abstract

The human parenting brain may undergo remodeling that supports the adjustment to new parenthood. In a longitudinal study of new mothers (Hoekzema et al., 2016), gray matter volume decreases were observed in first time mothers followed from pre-conception to early postpartum in a number of structures, including the left hippocampus. The left hippocampus was the only structure to show grey matter volume recovery at two years postpartum, in keeping with evidence from rodents that the hippocampus is unusually plastic across reproductive transitions. There is a small research literature suggesting that fathers may show brain changes around the perinatal period, although several studies have pointed to individual differences within fathers that may reflect adaptation to parenthood, rather than main effect changes distinguishing fathers from non-fathers. However, no studies have focused specifically on hippocampal volume changes in new fathers.
Among 37 first time expectant fathers scanned before and after having their first child, we calculated left hippocampal brain volume in the men during their partners’ pregnancy and then again at six months postpartum. There were no significant differences in left hippocampal volumes across the whole sample but individual differences in prenatal-to-postpartum volume changes were associated with parenting-relevant constructs. Greater grey matter volume increases in the left hippocampus predicted better postpartum parenting outcomes, including stronger father-child bonding and attachment and lower parenting stress. Fathers who reported that they came from more harsh, cold, and conflictual childhood family environments showed smaller increases in hippocampal volume across the transition to parenthood. In contrast, higher levels of prenatal oxytocin, a social affiliative neuropeptide which has been associated with preparation for parenting in other samples, predicted greater volume increases. Increases in left hippocampal volumes were also correlated with declining levels of testosterone from prenatal to postpartum. Analyses were repeated with the right hippocampal volumes but did not yield significant results, suggesting that these findings are specific to the left hippocampus. In short, change in the left hippocampus may reflect individual differences in fathers’ life histories and hormones, and may predict better adjustment to parenthood.

Authors

• Darby E. Saxbe, University of Southern California
  Presenting Author

• Magdalena Martinez Garcia, Hospital Gregorio Marañón

• Sofia Cardenas, University of Southern California

• Yael Haya Waizman, University of Southern California

• Susanna Carmona, Hospital Gregorio Marañón