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 sooner. Fatherhood changed him; it gave his life purpose, he said. It turns out neuroscience agrees with him.
My research lab investigates how the brain changes when men become fathers, and we are discovering that fatherhood can be transformative for their brains and bodies. The brain and hormonal changes we observe in new dads tell us that nature intended men to participate in child-rearing, because it equipped them with neurobiological architecture to do so. They too can show the fundamental instinct for nurturing that’s often attributed solely to mothers.
Not only that, but men’s involvement in fatherhood can have long-term benefits for their brain health — and for healthy societies. At a time when boys and men seem to be experiencing greater social isolation and declining occupational prospects, the role of father can provide a meaningful source of identity. But the transition to fatherhood can also be a time of vulnerability, which is why supporting fathers should be a priority for policymakers.
In a 2022 study, my colleagues and I collaborated with researchers in Spain to gather brain scans of a small number of first-time fathers before and after their babies were born. Our results echoed studies of mothers done by some of the same researchers. In several landmark studies, they found that as women became mothers, their brains lost volume in gray matter, the layer of brain tissue rich with neurons, in regions across the brain, including those responsible for social and emotional processing.
Although a shrinking brain sounds like bad news, less can be more: These changes might fine-tune the brain to work more efficiently. The teenage brain also trims down its gray matter as it develops. Women who lost more brain volume showed stronger attachment to their infants after birth, indicating that the shrinkage promoted bonding.
Our findings for fathers were similar. Men also lost gray matter volume in new fatherhood, in some of the same regions that changed in women. But volume reductions for dads were less pronounced. The findings for mothers had been so striking that a machine-learning algorithm could tell mothers and nonmothers apart by their brain scans alone. The picture was noisier for fathers. My hunch is that men’s brain changes looked less clear-cut because fathers vary so much in their levels of engagement in parenting.
We tested that theory in a follow-up study where we measured how dads felt about their babies before and after birth. When fathers told us that they felt more bonded to their unborn child and hoped to take more time off from work after birth, they went on to lose more gray matter volume across the cortex — the part of the brain that does higher-order thinking. Similarly, fathers who spent more time tending to their infants in the three months after birth showed larger gray matter reductions. Fathers who lost more gray matter volume also said they enjoyed their infants more and reported lower parenting stress.
But a shrinking paternal brain may also have downsides. We found that fathers who lost more gray matter volume had worse sleep and more symptoms of depression and anxiety in the first year after birth. More studies with larger samples of men are needed, but our preliminary takeaway was that the same brain adaptations that seemed to track with engagement in fatherhood also signaled risk to men’s well-being.
Infant care can be exhausting and isolating, so it makes sense that it might take a toll on involved fathers, just as it can on mothers. Our lab has found similar patterns for men’s testosterone, which can dip around the transition to new fatherhood. Dampened testosterone seems to bolster fathers’ investment in parenting, yet also may confer risk for postpartum depression.
Even so, most fathers tell us that they derive tremendous meaning and purpose from their connection to their children. Contemporary fathers are almost as likely as mothers to say that parenthood is central to their identity, and men are even more likely to report that children improve their well-being than women are. And the newest data suggests that parenting may ultimately promote long-term brain health; among older men and women, a brain-age algorithm estimated that the brain looked younger among people who had children.
The take-home message for men is that brain change is likely a good thing, even if it exposes vulnerability. Podcasters and pundits have exhorted men to pump up their manliness by raising their testosterone through cage fights, ice baths, weight-lifting and red light therapy, but these influencers miss the mark on men’s health. A well-lived life requires a physiology that adapts to changing demands.
My lab has interviewed over 100 men about becoming a father, and a recurring theme is “transformation.” I’ve seen it firsthand: After my own parents split up in the 1980s and agreed on joint custody, my formerly checked-out dad became a solo parent on alternating weeks. If you ask him about that experience now, he calls it a great joy. We taught him patience and fortitude, he’ll say. (My siblings and I were really obnoxious.)
Transformation requires time and practice, which is why healthy societies invest in policies that promote bonding and reduce stress in early parenthood, like family leave and workplace cultures that allow fathers to prioritize parenting. To most effectively champion families, we must recognize that fatherhood changes men just as it changes women and anyone else who devote time to caring for young children. At a time when birthrates are dropping and people feel lonely, the role of father offers an anchor, grounding men in their relationships with others.
Darby Saxbe is a professor of psychology at the University of Southern California. She is writing a book on how fatherhood transforms men.
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