Family

How Babies Mess With Everybody’s Brains

Author Chelsea Conaboy on the neuroscience of caregiving.

A father and mother in bed with a smiling baby
Mladen Zivkovic/iStock/Getty Images Plus

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Chelsea Conaboy’s new book, Mother Brain: How Neuroscience Is Rewriting the Story of Parenthood, is an ambitious look at new science investigating how caregiving changes everyone who does it. Conaboy draws on research from neuroscience and psychology to make sense of the challenging transitions of early parenthood. The book weaves together stories of Conaboy’s own early years of motherhood with interviews with a diverse group of mothers, including a woman whose own mother had died shortly after giving birth to her brother, a woman whose newborn spent time in the neonatal intensive care unit, and people who became parents during the early days of the pandemic.

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Conaboy, a journalist who was part of a group of staffers at the Boston Globe that won a 2014 Pulitzer for coverage of the Boston Marathon bombings, lives in Maine with her husband and two sons. I spoke with her about the emerging science of brain changes in fathers, why maternal instinct is an outdated and unhelpful concept, and what she wishes legislators and policymakers knew about the caregiving brain. This conversation has been condensed and edited for clarity.

Nancy Reddy: Could we start by talking about how the book developed? You published a piece in the Boston Globe in 2018, “Motherhood Brings the Most Dramatic Brain Changes of a Woman’s Life,” that focused on such shifts in mothers and asked why that information wasn’t part of prenatal care. I think in that piece you’re talking pretty specifically about gestational parents, but your book is much bigger in scope, looking at fathers and adoptive and foster parents as well.

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Chelsea Conaboy: With that 2018 story, I was at a place where I was trying to figure out my own experience. That started because I felt really consumed by worry in those early postpartum weeks, and not only that, but I felt this fundamental shift within me that I just didn’t have the words to describe. So, I went looking for answers and fell into this research, particularly looking at maternal anxiety. Then within that research, I looked at how the brain changes for everyone who has given birth to a baby, not only for people who experience perinatal mood and anxiety disorders. So that piece was really about dissecting my own experience and asking, Why didn’t I know about this research sooner?

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But then, as I wrote the book proposal, I knew I wanted to talk about fathers and other parents too, because there’s such interesting research around them. The brain changes in parenthood, and a lot of that is related to experience. Parents who invest their time and attention in their babies, even if they’re not gestational parents, their brains change too. So it just became this bigger question of not only do we fail to give gestational mothers the information that they need to prepare for parenthood, not only have we gotten this really limited view of what a “mommy brain” is, but also, we’ve also dramatically mischaracterized whose biology enables them to be really good caregivers.

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What are some of those changes that come about through caregiving?

This research really comes from a behavioral perspective, not just a neurobiological one, and first comes out of research that was done back in the ’60s by Jay Rosenblatt. He studied rats, and was trying to figure out the timing and hormonal involvement of more maternal behaviors. By accident, he ended up realizing that virgin rats also would become maternal if they just had time with pups, and so did male rats, even though they aren’t involved at all in caring for pups out in the wild. He wrote that maternal behaviors are a basic characteristic of the rat species. That is an idea that carries through in the animal literature and has borne out in humans as well.

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Obviously, we know that [human] fathers can be involved, that they have those behavioral changes, that they can become very invested in their kids. It’s still a somewhat small body of research, but what it’s pointing to is that fathers go through significant hormonal changes also, from before pregnancy, before they become fathers, to afterward. We’re starting to see changes in both the structure and the function of their brains.

There’s a significant study that came out of Israel that looked at different-sex couples and then same-sex couples who were men. Basically, they found general activation of important brain regions for caregiving across all of the parents, but between the mothers and fathers who were in different-sex couples, there were differences specifically around the amygdala, which is known to be really important for attention and vigilance in new mothers.

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But when the researchers looked at primary caregivers, whom they classified as the mothers, and the gay fathers (because there was no maternal involvement in those couples), they found really remarkable similarities in the amygdala activation. They found that there was kind of a dosage effect across all fathers. The more a father spent time being directly responsible for caring for their child, the more connectivity they found between the amygdala and the cortical brain region that’s really important for reading social cues in another person.

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There’s new research coming out that found structural changes in the brains of fathers scanned before and after their children were born, and interactions with oxytocin. We’re learning this still, but the research is definitely pointing to the idea that fathers are changed by caregiving too.

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One thing that I was really struck by in the book was the story you tell about oxytocin. So often people say, Oxytocin is the love hormone. You give birth and then you breastfeed and it bonds you to your baby, and it’s this magic and also very gender-specific kind of hormone. Could you talk about the more complex story of oxytocin?

First of all, it’s not gendered. We know men also experience spikes in oxytocin when they’re interacting with their babies and also shifts in their oxytocin as they anticipate fatherhood and become a father. Sari van Anders, one of the researchers I quote in the book, talks about how there are hormones, the things that are in our bodies, and also hormones as rhetoric. Oxytocin is one where we have really strong rhetoric attached to it—exactly as you just described—that your baby arrives, they put them on your chest, and you’re flooded with oxytocin and there’s your bond. It seals the deal, that golden hour.

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As I read more and more about the research, the thing that I found was that it’s just much more complicated than that. Oxytocin is important, but it’s not a love hormone. It is acting at the same time that we are having dramatic changes in estrogen and progesterone, and then it influences dopamine, and dopamine is an incredibly important piece of this picture.

You also write about research showing that oxytocin levels aren’t higher for breastfeeding parents compared to formula feeding, and that mothers don’t generally have higher oxytocin levels than fathers. And that was fascinating to me because I feel like this is one of the big myths around oxytocin, that you produce it by breastfeeding.

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It does have a role in breastfeeding. But the other point is, it’s not like oxytocin from breastfeeding is the one way to get [oxytocin] to the parental brain. Sure, it’s important. And in that context it has an important role to play. But for example, prolactin is thought to be involved in fathers bonding with their babies. We think of that as a milk-making hormone. But it’s been hijacked in fathers to do something different. Darby Saxbe, who studies fathers and does other interesting work about couples and social relationships, told me that one of her professors told her that any important system is going to be redundant, and parenting is so important for the survival of the species that there will be redundancies. So yes, you can experience bonding with your baby through breastfeeding and the oxytocin that provides, and then there’s going to be other ways to get to that bond also.

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You recently published an essay in the New York Times, “Maternal Instinct Is a Myth That Men Created.” When you talk about maternal instinct, what do you mean?

I was talking about maternal instinct as this idea, as it was written into instinct theory in the early 20th century, of a caregiving ability that is innate, automatic, and distinctly female. That is the “myth.” I think there is a creep of the definition of maternal instinct.

[Some critics of my Times essay] assumed that to get to the conclusion that maternal instinct is a myth, I had to disregard biology entirely. But I have written a whole book that is about the physiological changes that accompany parenthood and that we go through. Those things are real and so is that intensity, that vigilance many of us feel with a newborn.

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The thing is that that old definition of maternal instinct does not match the reality of what it means to go through that transition. So I think because there’s so much attached to that old definition, it’s time to retire it. We need a new way of talking about it because people mean different things when they’re talking about maternal instinct and because it’s rooted in these really gender-essentialist notions of womanhood. The transition to parenthood does propel us into this new stage of development that helps us adapt to this role, but it’s not automatic and it doesn’t feel innate to so many of us.

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One of the things you talk about at several points during the book is the fact that assuming mothers go through this innate biological automatic change is bad for all parents. It’s bad for mothers and gestational parents. It shortchanges fathers. It doesn’t actually help anyone. It’s not accurate and it’s not helpful.

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I think it’s really bad for our individual experiences of parenthood. And it’s also really bad from a societal viewpoint. I really think that idea has held us back from the social policies that we need to support young families, like parental paid leave, for example.

What would you want policymakers or legislators to know about your research? Because certainly there are things that individual parents or individual families and communities can do, but a lot of what you talk about really is dependent on big structural changes as well.

I love to make the parallel with teenage brain research. In the past 20 years or so, we’ve learned a lot about how the brain changes during adolescence, and we’ve taken that information and we’ve used it to change school start times because we now know that the teenage brain needs more sleep, or to change how we talk about substance use, like public messaging around it and other risky behaviors. Some schools have even used it to change how they manage discipline in high schools. We’ve also taken this information to the teenagers to help them, and to parents to help them understand who they are and what they’re going through and what their needs are and what it means for their mental health overall.

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I think we need a similar conversation around parents. I think it could be part of prenatal education more. It could be part of how we talk to one another about parenthood. But then also if it’s true that new parenthood is this dramatic transition in your life, a major stage of development, then how would we change our clinical care? New parents are basically on their own after they leave the hospital. That’s not the case in other countries where there’s midwives and public nurses who check in on them, sometimes daily at the start, but at least frequently [moving on].

What about paid leave? This is a major upheaval for the brain. It’s obvious in every other way, also, that families require paid leave. And also affordable child care. One of the researchers I talked to about this talks about specialized baby tenders and recognizing the value of the people who can care for babies, not just parents. Can we build up affordable child care in a way that really recognizes the value of the people who do this specialized work of taking care of babies? It is a practical skill, and it is a cognitive skill to be able to do it well. So let’s value the people who do that work that’s so essential to the health of our families and the health of our society.

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Correction, Sept. 14, 2022: This piece originally linked to a different study by the research team looking at fathers’ brains. The updated link is more directly relevant to the topic.