Fatherhood alters brain structure, increasing both bonding and mental health risks

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New research reveals that first-time fathers experience significant changes in their brain structure. The study, published in the journal Cerebral Cortex, found that fathers who felt a strong bond with their unborn child and planned to spend more time with their baby after birth showed notable decreases in certain areas of their brains. These changes were associated with both positive parenting behaviors and increased risks for sleep problems and mental health issues.

Most research on parental brain changes has focused on mothers, who undergo significant hormonal and physical changes during pregnancy and postpartum. However, understanding how fathers’ brains adapt to parenthood can provide insights into how parental involvement and bonding affect brain structure. Fathers gain parenting experience without the physiological changes of pregnancy, making them a unique group to study.

“I am interested in studying neuroplasticity across the lifespan– and the parenting brain is a great example of that. I think fathers are particularly interesting to study because they do not experience pregnancy directly, but they are still involved in infant care. Also, there is variability across fathers in terms of their time with infants and bond with their children,” said study author Darby Saxbe, a professor at the University of Southern California and head of the NeuroEndocrinology of Social Ties Lab.

The study involved 38 men transitioning to first-time fatherhood, all cohabiting with their pregnant partners in California. Participants underwent high-resolution MRI scans during their partner’s pregnancy and again between 6 to 12 months postpartum. In addition to the brain scans, the men completed self-report questionnaires during pregnancy and at 3, 6, and 12 months postpartum. These questionnaires assessed factors such as bonding with the unborn child, parenting stress, time spent with the infant, sleep quality, and mental health.

The researchers found significant reductions in cortical gray matter volume across the entire cortex in new fathers, particularly in the frontal, temporal, and parietal lobes, as well as the cingulate cortex. These reductions were more pronounced in fathers who reported stronger prenatal bonding with their unborn child and those who planned to take more time off work after the birth. Specifically, the left frontal, right parietal, and right temporal lobes showed the most substantial volume decreases.

Fathers who spent more time with their infants, especially as the primary caregiver, also experienced greater gray matter volume reductions. Conversely, higher levels of parenting stress were associated with smaller cortical volume reductions. These findings suggest that brain changes in new fathers are linked to their parenting motivation and engagement, reflecting successful adaptation to parenthood.

However, the study also revealed a downside to these brain changes. Larger cortical volume reductions were associated with worse sleep quality and higher levels of depression, anxiety, and psychological distress at three, six, and twelve months postpartum, even after controlling for prenatal mental health and sleep quality. Interestingly, fathers of older infants at the time of the follow-up scan had smaller cortical volume reductions, indicating a potential rebound in gray matter volume.

“We found that the volume of grey matter tissue in the cortex decreased slightly (on average by about 1%) from pregnancy into the postpartum period in first-time fathers,” Saxbe told PsyPost. “Fathers who lost more volume reported more time with infants and stronger feelings of bonding, which is consistent with the research on mothers. However, those same fathers also reported more sleep problems and symptoms of depression and anxiety, suggesting that the brain remodeling associated with fatherhood may also expose mental health vulnerabilities.”

The study, like all research, had some limitations. The sample size was relatively small, and the COVID-19 pandemic disrupted the planned timeline for data collection, resulting in some fathers being unable to complete their follow-up scans on schedule. The researchers did not include a control group of non-fathers, which would have strengthened the findings by providing a direct comparison. Additionally, the study used a specific approach to measure brain volume, focusing on cortical rather than whole-brain analyses due to potential scanning artifacts.

Despite these limitations, the study’s longitudinal design and detailed self-report data provide valuable insights into how the transition to fatherhood impacts the brain. The findings suggest that while brain changes in new fathers are associated with positive parenting behaviors, they may also increase vulnerability to sleep and mental health issues.

The study, “Cortical volume reductions in men transitioning to first-time fatherhood reflect both parenting engagement and mental health risk,” was authored by Darby Saxbe and Magdalena Martínez-Garcia.


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