The following essay is reprinted with permission from The Conversation, an online publication covering the latest research.
The time fathers devote to child care every week has tripled over the past 50 years in the United States. The increase in fathers’ involvement in child rearing is even steeper in countries that have expanded paid paternity leave or created incentives for fathers to take leave, such as Germany, Spain, Sweden and Iceland. And a growing body of research finds that children with engaged fathers do better on a range of outcomes, including physical health and cognitive performance.
Despite fathers’ increasing involvement in child care and their importance to the lives of their children, there is very little research on how fatherhood affects men. Even fewer studies are focused on biological changes and brain functions that may support fathering.
It’s not surprising that the transition to parenthood can prove to be very difficult for anyone who has a baby. Pregnancy-related hormonal changes are a reason why a mother might have a different brain than if she was a biological mother. What happens to fatherhood? Does it affect the brains and bodies, even if they don’t experience pregnancy directly? If so, how does this impact their parenting? We set out to investigate this question in our recent study of first-time fathers in two countries.
Pregancy’s effect on a new mom’s brain
Recent research has found compelling evidence that pregnancy can enhance neuroplasticity, or remodeling, in the structures of a woman’s brain. Using magnetic resonance imaging, researchers have identified large-scale changes in the anatomy of women’s brains from before to after pregnancy.
In one study, researchers from Spain examined first-time mothers just before they conceived and again two months later. Compared with childless women, the new mothers’ brain volume was smaller, suggesting that key brain structures actually shrank in size across pregnancy and the early postpartum period. The brain changes were so obvious that an algorithm could easily distinguish the brains of women who had experienced a pregnancy from those of women without children.
These changes can be seen in gray matter, a layer of tissue that is rich in neurons, all over the brain. Pregnancy appears to affect structures in the cortex–the most recently evolved, outer surface of the brain–including regions linked with thinking about others’ minds, a process that researchers call “theory of mind.” Mothers also show brain changes in the subcortex – the more ancient structures nestled deeper within the brain that are linked with more primitive functions, including emotion and motivation.
Why do these structural brain changes occur after pregnancy?
Researchers believe that these brain changes could help mothers care for newborns who are constantly in need of their attention and cannot communicate their needs verbally. Indeed, when mothers see photos or videos of their own infants, it activates many of the same brain regions that changed the most across pregnancy. It is possible that mothers’ brains may change in ways that help them care for and respond to their newborns.
But, what about fathers.
But what about fathers? They may not experience pregnancy directly but may be involved in caring for the baby.
Dads’ brains change, too
As with any new skill, caring for an infant can leave a mark on the brains and minds of parents. This is what neuroscientists refer to as experience-induced brainplasticity. It’s similar to the brain changes that occur when you learn new languages or master a musical instrument.
A growing body of research is looking at this type of plasticity in fathers who are able to care for a newborn without having to go through pregnancy. In terms of brain function, for instance, gay male fathers who are primary caregivers show stronger connections between parenting brain regions when viewing their infants, compared with secondary male caregivers.
To learn more about plasticity in new dads’ brains, our research groups at the University of Southern California in Los Angeles and the Instituto de Investigacion Sanitaria Gregorio Maranon in Madrid, associated with the BeMother project, collaborated on a new study. We recruited 40 men–20 in Spain and 20 in California–and put each into an MRI scanner twice: first during their partner’s pregnancy, and again after their baby was 6 months old. We also included a control group of 17 childless men.
We found several significant changes in the brains of fathers from prenatal to postpartum that did not emerge within the childless men we followed across the same time period. Both in California and Spain, brain changes were seen in the cortex of fathers. These regions are responsible for visual processing, attention, and empathy towards the baby.
What remolds a new father’s brain?
Fathers’ brain plasticity may be related to how they interact with their child. While fathers in many countries are taking more part in child care, the level of paternal involvement in different men is variable. This may be why we observed subtler brain changes in these fathers than in first-time mothers. Brain changes in fathers were nearly half of those observed in mothers.
Social and cultural factors can influence how fathers interact with their children. Indeed, Spanish fathers, who, on average, have more generous paternity leaves than fathers have in the U.S., displayed more pronounced changes in brain regions that support goal-directed attention, which may help fathers attune to their infants’ cues, compared with Californian fathers.
This finding raises the question whether family policies that increase the amount of time dads spend caring for infants during the first few weeks after birth may be beneficial in supporting the development of the fathering mind. On the flip side, perhaps men who show more remodeling of the brain and hormones are also more motivated to participate in hands-on care.
More research is needed to answer these questions and figure out how to best help fathers who are having difficulty adjusting to their parenting roles. Although fathers are crucial to child development, funding agencies have not prioritized research on men becoming fathers. However, this could change as more evidence is available. Future studies that include more detailed measures of postpartum caregivers will be able to reveal more about parental brain development in both men as well as women.