Expecting: Baby brain
27:55 Share

On September 28th, the Global Citizen Festival will gather thousands of people who took action to end extreme poverty. Join Post Malone, Doja Cat, Lisa, Jelly Roll, and Raul Alejandro as they take the stage with world leaders and activists to defeat poverty, defend the planet, and demand equity. Download the Global Citizen app today and earn your spot at the festival. Learn more at globalcitizen.org.com.

Since World War II, countries like Cuba have used shortwave radio to communicate with their spies. If you have the code, those numbers obviously are all words, and they were instructions to Ana, and that told her where to look and what to do that particular week. This week on Criminal, the story of a woman who spied on the U.S. government for 17 years and how she was caught.

Listen to our latest episode, Anna, wherever you get your podcasts. Hi. Hi. Hello. A few months ago, we reached out to listeners to ask how becoming a parent had changed them. We got a lot of responses with people describing a whole range of changes.

I feel like I was actually aware of my brain expanding and receiving and understanding new information. I found that I am far more sensitive to

Before she was born, I never cried at movies.

Even the really sad ones. My Girl, that movie from the 90s where the kid dies from the bees. Everyone cried at that movie. I never did. And then my daughter was born and now I cry at everything. Dog food commercials have done it and made me cry.

Some listeners told us they were more exhausted or more stressed. Others told us they were actually less stressed. A bunch of listeners said they could no longer listen to true crime if it involved a child. Suddenly, every baby is your baby. But for most of our listeners, we heard one thing especially clearly. My brain has...

definitely changed since having the baby. Gosh, everything changed. My brain changed for sure. I don't even know where to start. Everything's completely different. And now, this is probably not a surprise, right? Like, most parents could probably tell you a story about how parenting changed them. What is maybe more surprising is that these changes are still relatively under-researched and not particularly well understood.

But as researchers have started to poke around in the brains of pregnant people and caretakers of kids a little bit,

They've realized that becoming a parent changes our brains in structural and functional ways. This is Chelsea Conaboy. She's a health and science journalist, and she's also a mother. And when she had her first kid, she kind of dove into the research on parents' brains, like so deep that she ended up writing like a whole book about it.

And in that process, she found more and more evidence for this big sort of relatively new hypothesis that becoming a parent is not just sort of a little forgetfulness or like a lot of exhaustion.

It's potentially a whole new developmental stage, which means that parenthood might be kind of a radical shift in who a person is, where they develop like new behavior patterns, for example. And in fact, it's a developmental stage that is as distinct as adolescence, and it shapes us for the whole rest of our lives.

But in her reporting, Chelsea also realized that we know very, very little about what that means for parents' personalities or their emotions or even their mental health. There's so much left to learn, not only for pregnant people, but also for other non-gestational parents. I think we're still on the brink of understanding what this really means for the rest of our lives.

This is Unexplainable. I am Bird Pinkerton. And this is the second episode of Expecting, our series about pregnancy. In the last episode, we looked at how fetuses in the womb affect their parents on a cellular level. But this week on the show, we are going to look at how children might continue affecting their parents' brains long after they have exited the womb. ♪♪

So let's start with what we know here. In the last few decades, scientists have gotten a lot more information about how infants change their parents' brains because they actually have tools that let them look at those brains. So they've used brain imaging technology to sort of peer inside parental skulls and see changes to the brain's architecture. Basically, it's structure. In terms of structure,

There's been a fascinating set of studies that were published by researchers in Spain that I think are going to become like landmark for this field. One of these studies was published in 2016, and it focused on a small sample of specifically women. So 25 women who had given birth to infants and were raising them.

And basically, the researchers took images of these women's brains before they got pregnant, and then right after the women had their babies, they took more images.

And then for some of the women, they took even more images a few years down the line. And what they found across pregnancy was that there was a significant loss in gray matter volume. Which sounds bad, right? Like gray matter is this sort of like wrinkly part of the brain that has lots of neurons. It's involved in information processing, like blood.

losing gray matter might seem concerning. And when they first published this piece, they were overwhelmed by responses from people saying, oh, volume loss, like that explains why I can't remember anything. This is actually a trope that's really common in pop culture, this idea that there's kind of a brain fog that comes with parenting. She's got a serious case of pregnancy brain. Pregnancy brain. Pregnancy brain. So

So basically, it's this idea that pregnancy has a negative effect on the brain. And they were like, no, no, that's not it. That's not the point here. Volume loss can be associated with stuff like dementia. Losing gray matter specifically does not always mean that the brain is working less well. In fact, these researchers thought that this particular kind of loss of gray matter that they were seeing was

It reminded them less of dementia and more of the rewiring changes that teenage brains go through during puberty. Because teen brains also lose gray matter. And specifically during adolescence, it correlates with a fine-tuning, a pruning away of synapses that aren't needed anymore and a strengthening of those that are needed. And like...

Teens do do some pretty wild things, but in general, we think of the teenage brain as developing and changing in ways that, like, prepare them for the next stages of life. Like, in teens, the sort of pruning of gray matter is not a bad thing. So this Spanish group was sort of curious to see how strong this parallel might be. Like, how similar was this kind of pruning in parents' brains to the pruning in teen ones?

And so what they decided to do was take their images from mother brains and compare them to images of brains from both teenage girls and brains of women without kids. And they found that in terms of like the scope and scale of volume loss in mothers and adolescent girls, it was very similar. Yeah.

This doesn't necessarily mean that the exact same kinds of changes are happening in the brain when someone becomes a teen versus a parent. But the scale of what happens across pregnancy and early parenthood is similar in terms of the degree of change of what happens during adolescence. Now, a lot of these studies have small sample sizes. There's a lot more research to be done. But for now, the tentative takeaway is that

having an infant seems to change the brain's architecture in some way. And then there's research that suggests kind of a further finding here. This is in even more early stages, but it suggests that these changes they're seeing in the brain

might not come just from the pregnancy itself, or at least not entirely. There's a study that was just published from some of the same researchers who did that really important structural work in mothers, and this looked at fathers across time. To be more specific, these were men who were not the gestational parent for their kid, but they were caretakers.

And the researchers used MRI machines to get pictures of these men's brains at a few different points in time, basically like during their partner's pregnancy and then again in the months after the baby was born. And they again found volume loss across that time period. Now, the results here were not as clear-cut as they were in the studies of the moms. Like, they did see some volume loss, but the results were a lot more mixed.

We can think of this study, though, as a suggestion that while the experience of pregnancy is really intense, it's possible that the changes in the brain may not just be limited to the parent who carries the fetus. It seems like something about caring for an infant might also change the brain, whether or not that infant sat in a person's womb. I didn't used to cry. I was a typical man. Now, anything and everything they do...

makes me cry at the drop of a hat. I can cry about almost anything.

And again, there is still a lot more research to be done here to kind of nail down exactly what these structural changes are, how widespread they are, whether this all holds up if you're sort of looking at bigger groups of people. But this idea that there are structural changes leads to kind of an interesting follow-up question, right? Like, if the brain is changing physically, is it also changing how it acts, right? Like, are there changes in how parental brains think?

And that is after the break.

You might want to try Greenlight. Greenlight is a debit card and money app that's made for families. Parents can send money to their kids, they can keep an eye on kids' spending and saving, and kids and teens can build money confidence and lifelong financial literacy skills.

Oda Sham is my colleague here at Vox, and she got a chance to try out Greenline. There are videos you can watch on how to invest money. So we took a portion of his savings to put into investing where I told him, watch the videos so that he can start learning how to invest money as well.

Millions of parents and kids are learning about money on Greenlight. You can sign up for Greenlight today and get your first month free trial when you go to greenlight.com slash unexplainable. That's greenlight.com slash unexplainable to try Greenlight for free. greenlight.com slash unexplainable.

Hey, unexplainable listeners. Sue Bird here. And I'm Megan Rapinoe. Women's sports are reaching new heights these days, and there's so much to talk about and so much to explain. You mean, like, why do female athletes make less money on average than male athletes?

Great question. So, Sue and I are launching a podcast where we're going to deep dive into all things sports, and then some. We're calling it A Touch More. Because women's sports is everything. Pop culture, economics, politics, you name it. And there's no better folks than us to talk about what happens on the court or on the field.

and everywhere else too. And we're going to share a little bit about our lives together as well. Not just the cool stuff like Met Galas and All-Star Games, but our day-to-day lives as well. You say that like our day-to-day lives aren't glamorous. True. Whether it's breaking down the biggest games or discussing the latest headlines, we'll be bringing a touch more insight into the world of sports and beyond. Follow A Touch More wherever you get your podcasts. New episodes drop every Wednesday.

So caring for an infant might reshape your brain, kind of change the architecture in there a little bit. But are parental brains actually doing anything different, right? Are they thinking differently in some way?

Chelsea Conaboy found some researchers who are trying to answer that question. And she walked me through what she found, starting with kind of the trope that we mentioned before. "Pregnancy brain." "Pregnancy brain." Again, this idea that pregnancy kind of makes your brain foggy. "The research that we have so far shows that specifically during pregnancy, on average, small and temporary deficits in memory loss are real." At least for some people.

And this could be because this part of your brain called the hippocampus, which is associated with memory, apparently kind of shrinks a bit during pregnancy. But the hippocampus also seems to rebound afterwards. And so Chelsea says that the emphasis should be placed on sort of temporary and temporary deficits.

But meanwhile, she heard from other scientists about other potentially more permanent changes that are kind of being overlooked. The frustrating part of this like mommy brain narrative is like, OK, so those average temporary deficits may be real, but they're really just like one small piece of the picture here of like the cognitive changes that happen through parenthood.

The bigger picture is that a lot of the structural changes that researchers spotted in the brain of both gestational and non-gestational parents, the changes that could be a little longer lasting, those are in areas that are related less to memory and more to kind of like social cognition. How we understand other people's mental states and emotions and reflect those things in ourself. There have been a bunch of studies around this.

And they rely on fMRI, so functional MRI, which is basically where you stick a person in an MRI machine and kind of see which parts of their brains are most active when they interact with stuff. And in these studies, researchers took moms who had given birth to babies and were kind of their caregivers, and they popped them into fMRI machines to kind of take a peek at their brain activity. ♪

And then they also looked at brain activity from people who were not caregivers for children, so kind of like non-parents. And they compared how these two groups reacted to a variety of things. Baby stimuli and non-baby stimuli. So while they were in the machine, these subjects were sort of playing sounds, for example. Like a baby's cry versus some other harsh sound. Yeah.

Mothers were also shown different faces. There's often a lot of studies that do like known versus unknown babies. So like your own baby versus another baby's face, smiling or crying.

Overall, these studies found that the moms' brains kind of reacted differently than the brains of the non-parents. Like, social and emotional parts of their brains were reacting more strongly to baby-related sounds and images, especially sounds and images from their own babies. So it seems like their brains had changed to become, like, super hyper-zoomed in to the social and emotional needs of infants, which...

Makes sense, right? Like parenting is this intense exercise in paying attention to kids. It's thought that all of this, like paying attention to our babies, fine-tunes our capacity to read and respond to their cues so that we can change with them over time. Their cues are constantly changing and we need to be really good at understanding them. And also at the same time,

be better at regulating our own emotions in the process because that's really hard work. And here again, there are some preliminary studies that suggest that the kind of key ingredient in all this is not pregnancy alone,

but kind of caregiving in general. Because there's not like a ton of research on non-gestational parents, but there are some studies here on gay dads. And those studies do show sort of changes in dads' brains in how they sort of react to their babies.

It really, like, affirms the idea that experience matters, that when we do the work, we experience this neural adaptation to help us be better at it. So that kind of loosely, broadly, is what we know so far, right? Like, caring for an infant may change sort of the structures of the brain and could change how the brain also interacts with the world. What we don't know is...

many other things. Even if we just take the finding that sort of parents are paying super close attention to babies, for example, does that mean they're only tuning into their babies or are they tuning into other social situations more too? The

The short answer is that we really don't know. But the researchers that I've talked to have said that they expect that this change in our social cognition probably applies to other particularly very close relationships as well. Chelsea says that maybe in theory, right, like spending all this time reading tiny, minute expressions and a being that can't talk makes you pay more attention to nonverbal cues all around you, right?

Or you could also be like, you know what? I only care about my baby. I don't care about anyone else. Like there aren't great answers here. And if people are changing, researchers also don't know how long those changes last, right? Like when you go through puberty, for example, you don't usually go back with a possible exception of a midlife crisis. But are these changes to the parents similarly permanent?

There's really like a whole gap in our understanding here. Like what we have is primarily focused on the early postpartum period. Which is to say like the research that we do have only looks at the first few months after an infant is born. The researchers who studied the sort of volume loss in mothers' brains did follow up with some of the mothers six years down the line.

and found that most of that volume loss, with some small exceptions, is preserved at six years out. So they've hypothesized that that may mean that these changes are permanent to some degree, but we really have like...

All of middle age, essentially, in parenthood is unstudied. Now, there are some studies that have kind of compared the brains of older adults. People in their 50s, 60s and 70s, well past their childbearing years. Researchers have used images of these brains from brain imaging data banks in the UK and Australia to look at the brains of people who have been parents and people who have not been parents.

And they found that the brains of parents were what researchers called younger-looking. Literally, like, the ways that the parts of the parent brains were, like, connected to each other and the size and volume of different parts of the parents' brains looked more like a young person. It's like a little fresher or more spry. And if you think about it, like, it makes sense. Parenthood is full of these individuals

intensely social, ever-changing cognitive challenges. So maybe parenthood is like doing a really great brain-boosting crossword puzzle for several decades. And over time, like, this is something that could be potentially healthy for the brain in terms of like

But again, this is all a lot of maybes, right? And who knows? Maybe it's possible that the people who are inclined to become parents have brains that skew younger looking or something, right?

Researchers are really just beginning to pull at all these underexplored threads here. But if they can answer some of these questions, like, maybe they could also help explain some of the things that make parenting so complicated and exhausting and exhilarating. Stuff like sleep, for example. We really don't know how sleep interacts with the changing parental brain.

Or, like, we could do a whole episode about how little we know about postpartum depression.

There isn't just one postpartum depression. There's probably lots of different postpartum depressions and all with different causes and potential treatments. We don't really understand how SSRIs, these like commonly prescribed antidepressants, how they function in the postpartum period. Partly because it seems like the serotonin system is changed by pregnancy. And so therefore it's really hard to know how those drugs work.

And what we do know is limited to like a pretty small portion of the population. Overwhelmingly, the research to date has been in white, middle class, cisgender, heterosexual women. This avalanche of questions just kind of reinforces something that I've encountered throughout reporting this series. Like over and over and over, I keep hitting up against the idea that

reproductive health is just underexplored and under-understood, which is weird to me. Like, pregnancy is this fundamental thing. Without it, none of us would exist. And yet having a kid is just this terrifying pit of mysteries. Like, Chelsea herself hit on some of the realities of this when she gave birth to her son in 2015. I just, I felt so...

Worried about taking care of this tiny, vulnerable baby who I loved completely, but was also terrified of, you know, the responsibility of caring for him. And for a while, that worry didn't go away. It kept growing. I worried about his growth and whether he was getting enough food. I also worried about the worry itself. She felt like there were just...

few good answers about what she was supposed to do, like how to be a good parent, how to take care of this tiny being. And for Chelsea, the kind of like research journey that she went on helped calm some of those fears. What I learned as I looked more closely at this research is that becoming a parent is a process.

And we are shaped by our babies as much as we shape them. But she agrees that the process of becoming a parent could be so much easier if we did have more answers. More answers about what is happening to the fetus or the baby, and more answers about what is happening to the parent when they have a kid. We deserve to have the information about how our bodies and our brains are changed by that. And

We also deserve to have that be part of the cultural conversation around what it takes to become a parent and how we as a society need to support people who are going through this really powerful developmental stage. Next week on our Expecting series, we'll have more of that cultural conversation about being a parent.

We're going to tackle kind of a narrow question, which is, can expecting parents smoke weed? But we'll use it to explore the ways that a lack of answers kind of shapes parents' lives in frustrating and sometimes pretty scary ways. Thanks again to Chelsea Conaboy for her help. If you want to read more about the research that's been done into parenting and brain development,

check out her book. It's called Mother Brain, How Neuroscience is Rewriting the Story of Parenthood. It also dives into the fascinating history around the idea of maternal instinct and how that idea led some researchers astray for decades. Thanks as well to all the listeners who reached out. We couldn't use all of your voice memos, but we really appreciated them.

Huge thank you to Rhea Ramjhan, Justin Cornelli, Gabby Simalik, Eduardo Alejandre, Melissa Lopez, Andy Nez, Allison Gennard, Hannah Martin, Alex, Alexis Cussman, Michelle Ball, Michelle Maring, Douglas Stickle, Sarah Poulton, Liz LaPointe,

This episode was reported and produced by me, Bred Pinkerton. It was edited by Brian Resnick and Catherine Wells, as well as Meredith Hodnot, who runs the show. We had sound design and mixing from Christian Ayala, music from Noam Hassenfeld, Serena Solon checked our fax, and Mandy Nguyen rhymes with everything nice.

We have more articles about pregnancy unknowns, and you can check out vox.com slash unexplainable to read them. You can also leave us a review or email us with your questions and thoughts at unexplainable at vox.com. We really love hearing from you, so please do that. Unexplainable is part of the Vox Media Podcast Network, and we will be back next week with another episode of Expecting.