A father of three recently told me that if he could go back in time and give himself one piece of advice, it would be to have kids earlier. He said that becoming a father has changed him, given him purpose in life, and neuroscience seems to agree.
In my lab, we are studying how the brain changes when a man becomes a father and finding that fatherhood can lead to changes in the male brain and body. The brain and hormone changes we see in new fathers suggest that nature intended for men to participate in child rearing because men are equipped with the neurobiological structure to do so. Men can also exercise the basic instinct for nurturing that is thought to be unique to mothers.
Moreover, men's involvement as fathers may have long-term benefits for their brain health, and for a healthy society. At a time when boys and men are becoming increasingly socially isolated and their career prospects seem to be worsening, the father role can be a source of meaningful identity. But the transition to fatherhood is also a vulnerable time, and supporting fathers should be a priority for policymakers.
In a 2022 study, my colleagues and I collaborated with researchers in Spain to collect pre- and post-natal brain scans of a small number of people who became fathers for the first time. Our findings were consistent with studies of mothers conducted by some of the same researchers. Several groundbreaking studies have found that when women become mothers, the volume of gray matter, a layer of neuron-rich brain tissue, decreases in regions throughout the brain, including areas responsible for social and emotional processing.
Although a smaller brain sounds like bad news, being smaller is a good thing. These changes may fine-tune the brain to function more efficiently. Teenage brains also shrink in gray matter as they develop. Women who experience greater brain volume loss are more attached to their infants after giving birth, suggesting that smaller brains strengthen the bond.
The results were similar for fathers. Fatherhood also reduced gray matter volume in some of the same regions that changed in women. But the volume loss in fathers was less pronounced. The findings for mothers were so striking that the machine learning algorithm could distinguish between mothers and non-mothers just from brain scans. For fathers, the picture was noisier. My intuition is that fathers' levels of involvement in childcare are so different that the changes in men's brains were less clear.
We tested that theory in a follow-up study that measured how fathers felt about their babies before and after birth. When fathers told us they felt more connected to their fetuses and wanted more time off work after the birth, they had greater losses in gray matter volume across the cortex (the part of the brain responsible for higher-level thinking). Similarly, we found that fathers who spent more time caring for their babies in the three months after birth had greater losses in gray matter. Fathers with greater losses in gray matter volume said they enjoyed spending time with their babies more and reported less stress from parenting.
“But there may be a downside to fathers' smaller brains: We found that fathers who experienced greater losses in grey matter volume reported worse sleep and more symptoms of depression and anxiety in the year after birth. Further research with larger samples of men is needed, but our tentative conclusion is that the same brain adaptations that appear to be linked to fatherhood involvement may also signal a risk to men's health.”
Raising an infant can be exhausting and lonely, so it's not surprising that fathers take on the same burden as mothers. In our lab, we've found a similar pattern in men's testosterone levels, which can decline before and after fatherhood. The decline in testosterone seems to increase fathers' commitment to parenting, but it may also put them at risk for postpartum depression.
Still, most fathers say they get a lot of meaning and purpose from connecting with their kids. Today's fathers are nearly as likely as mothers to say being a parent is central to their identity, and men are even more likely than women to say children improve their well-being. And new data suggests that parenting may ultimately promote long-term brain health: Among older men and women, the Brain Age algorithm estimated that the brains of those who have children appear younger.
The lesson for men is that changing the brain is probably a good thing, even if it exposes vulnerabilities. Podcasters and pundits have been urging men to boost their testosterone and masculinity with cage fighting, ice baths, weightlifting, and red light therapy, but these influencers are missing the point when it comes to men's health. To live a fulfilling life, we need a physiology that can adapt to changing demands.
In my lab, we've interviewed over 100 men about fatherhood, and a recurring theme is change. I've seen it firsthand. My parents divorced in the 1980s, and after agreeing to joint custody, my previously childless father became a single parent, taking turns on a weekly basis. If you ask him about the experience now, he'll tell you it's gratifying. He'll say we taught him perseverance and fortitude. (Me and my brothers were real assholes.)
Change takes time and practice. Healthy societies invest in policies that strengthen bonds and reduce stress before parenthood, like family leave and workplace cultures that allow fathers to prioritize childcare. To most effectively advocate for families, we must recognize that fatherhood changes men, just as it changes women and anyone else who spends time caring for young children. At a time when birth rates are falling and people are feeling lonely, the role of fatherhood supports men and grounds them in relationships with others.
Darby Saxby is a psychology professor at the University of Southern California and is writing a book about how fatherhood changes men.
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