Baby brain gets blamed for almost every stuff-up a mother makes in modern society. But Dr Sarah McKay argues that baby brain as we know it, isn't scientifically true. And, becoming a mother is actually one of the best things to happen to a woman's brain.
You can listen to this conversation with Sarah and Lou via our podcast or read it below.
Welcome to the podcast, Dr Sarah McKay. I am so excited to have you here today.
Thank you very much for the invitation.
You've written a book called Baby Brain. Can you tell us a little about yourself before we chat about the book? .
I am a neuroscientist, although I joke and say I'm retired because I no longer work in academic medical research and the lab. Instead, I run a business specialising in translating neuroscience research for people who are not neuroscientists. To do that work, I write books, do public speaking events, go on podcasts, post on social media–or all of those things.
I'm also a mother and a wife. I have two teenage sons who are 13 and 15. When I was about eight weeks pregnant with my oldest son, I left the research lab and moved into science communications. So, his life and my change of career run in parallel.
Wow, do you think it has been an advantage to be a neuroscientist and understand how your child's brain is changing? Or were you just as blind as the rest of us?
As the boys have gotten older, I think I've gained more perspective on it, partly because more research has emerged from neuroscience, psychology and human behaviour more generally.
Fifteen years ago, studies weren't done in a way that were necessarily as applicable to everyday life–where we could look at some research and go, "Hey, I can make meaning from that for my child.
So, when my boys were little, I was really just trying to survive. But now they're a little bit older, I do have an understanding and a way of parenting that's shaped by research. There's some very clear adolescent brain research I can tap into and draw upon, and it's enabled me to think: am I doing this right?
It's good to know their behaviour is completely normal–especially the older one who's super independent. And to understand what drives them. Their social and emotional skills are developing, and I just need to stand back and watch and trust that what I did when they were young will set them up for now.
If I didn't think about it in those terms, I'd perhaps be trying to cling on a little bit too hard. Especially with the older one who's just so independent and so capable. He's off doing things with his friends, and I have to let him do what he should be doing in this stage.
So, neuroscience has been a real gift to this stage of parenting, because you're always a new mother. There's always the next stage to get your head around.
Yes, that's so true. So tell me, why did you write this book?
The conception story of Baby Brain goes back to when I was writing my first book: The Women's Brain Book.
My publisher and agent approached me and asked what I would like to write about. Initially, I was reluctant to even write a book–it sounded like a lot of hard work. So they said, "Well, what have you written for an audience that resonated?" And I had written an article for the ABC about menopause and brain fog, and it had gone gangbusters. But I didn't want to write about menopause. And my agent said, "What about baby brain?" I dismissed that idea outright because I never experienced it–I didn't even know it was a thing. From my neuroscientific understanding, I dismissed it as a colloquial idea of forgetfulness. Because what would be the biological mandate or the evolutionary purpose of women becoming stupid when they have babies?
So, I ended up writing about the female brain from womb to tomb, looking at each developmental stage. At that point there was very little examining pregnancy and childbirth, and that developmental phase in women's lives.
However, halfway through writing the book, a paper was published. It was December 2016, and for me, it was one of the most significant neuroscience papers I have read. I highlight the story of that research paper in the first chapter of Baby Brain. The study compared women's brain structure before and after their first pregnancy and found the structure changed very significantly. Primarily in the parts of the brain involved with social cognition, empathy and theory of mind. That's reading social cues: what other people may be thinking, feeling or needing. The idea that pregnancy prepared our minds for motherhood was extraordinary to me.
Can you define baby brain? Because it's not just after you have a baby, is it?
No, it's not. My book is about all of the wonderful, positive benefits of pregnancy and motherhood on our brains. But the term baby brain is a colloquial definition. It can also be called Mumnesia in some countries, or Milk Mind, or in Scottish midwifery folklore, it's called Porridge Brain–which I thought was funny. But the general idea is that during pregnancy and motherhood, there's forgetfulness or fogginess and a sense that you're not feeling your capable cognitive self. It's largely a negative experience, with about 80% of women relating to it. And some women say, "Oh, I'm a grandmother who still has baby brain." But there's about 20% of women who don't report it. And I was in that 20%.
This field has been reasonably well researched. It's pretty easy to get women into the research lab before pregnancy, during pregnancy after pregnancy, and in motherhood and use standard cognitive tests on them. But generally, the tests don't find any evidence of women during pregnancy or motherhood showing any signs of what we would call cognitive decline or dementia or large-scale forgetfulness or memory loss.
Occasionally some studies find a tiny tiny drop in recall in the third trimester of pregnancy only. And only in some studies. But what's really important is that in those few studies where it is detected, it's tiny. Women may not even notice it themselves. Yet those stories have been thrown around in the media as significant memory loss, even if it was just statistically significant.
But what's interesting is that in that same trimester of pregnancy, some studies have found memory enhancement. Particularly the studies looking at baby-related items like the price of strollers or baby-related items: tests that are ecologically relevant to the third trimester of the first pregnancy. But of course, those studies don't get reported.
So we see this experience of women having what they call baby brain yet the research doesn't match that experience.
So what's going on?
There's a real paradox between this subjective reporting and the objective measurements–and there are various reasons that I step through in the book to explain that gap. And I think those reasons give us a real and interesting insight into motherhood.
How does your brain change post-pregnancy and in the first five years? Has it changed dramatically? Is it the same as it was when it was pregnant?
Well, the best way to describe the changes is by thinking about before and after pregnancy rather than how the brain changes from week one to year five. The biggest changes we see are in social cognition.
If you scan a woman's brain before and after a first pregnancy–and this is really important for data analysis but not so important for everyday discussions–you'll see the significant structural change in these brain regions which reflect brain plasticity.
Brain Plasticity is simply the brain changing in response to an experience, and in this case, it is the biological experience of pregnancy–primarily pregnancy hormones drive these changes. And we see this reorganisation happen in the scans, which looks like volume reduction in some regions of the grey matter of the brain–which is the wrinkly covering of the brain. That sounds really frightening because we think reduction loss equals degeneration, disease, depletion or decay. Whereas our understanding of neuroplasticity and the neurosciences is this: plasticity reflects reorganisation, reprioritisation, and streamlining. And sometimes, that looks like tuning and pruning, and a lesser volume does not necessarily mean loss. It can often mean the enhancement of a particular skill set. It can mean plasticity. We see exactly the same process in adolescence.
So the question then becomes: do those changes last?
The main cohort of women were studied before pregnancy and until their first child was six years old. And the studies focused on women who didn't have another child during those years.
The results show that up until six years postpartum, most of those changes are detectable. The brain didn't bounce back. But some other studies have found the grey matter does kind of bounce back in some areas. However, those studies haven't carefully teased out the first time pregnant women, the never pregnant…so there's some muddied data there.
So, I think we can safely say the brain changes stay for at least five or six years. But other studies look much longer term. They examine scans of older women: women in their 40s and 50s, and then elderly women in their 70s and 80s. And if you look at a massive data set, they can reliably detect which brain owner was female and had experienced motherhood.
Wow. So, from an everyday point of view, what does the reduction in grey matter mean?
There's a number of ways you can think about that. We can think: what do we see?
Normally when we see the brain learning and mastering a new skill, we actually see the brain requiring less cortical real estate–less brain power to perform that skill. As you get better at something, the brain gets more efficient. And if we use very clever types of brain scans that show how these different parts of the brain communicate with each other, we see they are very efficient and flexible and responsive. It's almost as if there is physical streamlining and functional streamlining.
So, how does that relate to how women are behaving?
It's very interesting because we're talking here about the social brain and social cues. The brain has changed because there's a new human that we're solely responsible for looking after. And the baby's born with only a few social cues. Crying is a very powerful social cue and pregnancy can tune our brains into responding to a baby's cry–especially your own baby.
And you know that feeling when something is so cute, you just want to squeeze it? There's this certain biological mandate for cuteness, and it's not just looking cute. It's also when a baby makes little gurgly noises–vocal cuteness. And that baby smell which is so amazing– that's olfactory cuteness. These are all a baby's social cues, and our maternal brain zones in on them because it's primed by all of these changes to almost forget about everything else. This is our job now–just keep the baby alive.
Many women like to think that once the baby's out, they can carry on and the baby will just fit into my life. But neurologically, you've been transformed. Everything has changed. It's not always obvious and it doesn't mean every woman is innately tuned into knowing instinctively how to care for a baby. But our brains are primed to learn pretty quickly what to do.
That's amazing. What do you think of the saying: If you want something done, give it to a busy mother. Is there any data on this idea?
I think that idea benefits a lot of other people.
The conversations being had by neuroscientists who study baby brain are shifting lately. Instead of considering this a neurological problem of deficit and cognitive decline, there's talk about the term being a description women use to describe feeling overwhelmed.
Women have been primed to expect that our brains can't function. If you forget something, you blame your brain. And it's not like we've been purposefully primed by the patriarchy to blame our brains when things go wrong, but essentially, that's quite a useful outcome for society. Because if something goes wrong, woman blames her brain. No one else needs to step up and lend a hand. And similarly with the idea of super mum–it alleviates everyone else of any responsibility. .
We've absorbed these gender stereotypes about reproduction and cognitive function since puberty. We blame our hormones from puberty through to menopause, regardless of whether the fluctuations are low, high or normal–we blame hormones when things go wrong. And we internalise the blame and blame our brains. There is this cultural stereotype we've absorbed and it makes us our own worst enemies because we'll just blame ourselves.
Yes, and I think this is such an important conversation.
I loved that chapter about aging gracefully because motherhood is for life. So Let's talk about the idea that you're carrying your children's cells in your body.
Yes, so that's microchimerism. It's a real thing. There was research looking at women who carry boys versus women who carry girls, but the women weren't identified to the researchers.
And they found boy mums had a slightly better cognitive score than girl mums, even though the girl mums are still scoring. Normally there just did appear to be a slight difference.
So the research paper was asking why.
Might the testosterone from the male fetus in some way alter the cognitive capacity? There were all sorts of ideas. Including this idea that we absorb and take onboard some of their hormones–we absorb some of their cells through our placenta, and you can detect the cells of your child that you carried in the womb. The researchers can check that by doing a quick DNA check to look for an X YY chromosome in mothers who have carried sons. And we can see that change lasts in a mother's body into late life.
I just think that's a really lovely idea–especially now as my boys are moving out into the world. There's a little bit of them that stays behind with me. But there's also the idea that some of my cells go into them. And for the second child or subsequent children, some of their older sibling's cells from the mother can go back into the second sibling in Utero. So my younger son carries some of my oldest son's cells, but not vice versa.
And of course, the mothers of daughters will also carry those cells–they're just harder to detect.
Do you think this affects connection?
Probably not. It's a new finding, so I don't know whether we have enough evidence to say that, but I think it's a nice idea that they're still part of you.
The idea of connection I talk about in the chapter on brain-to-brain synchrony and physiological synchrony, is this idea that when you're connected with someone you have trust and rapport with, it carries through the lifespan. Particularly when it's established well in early life between a mother and a child, or a parent and a child.
But as one of the researchers said to me, "The connection isn't created by esp; it's not magic. You can interfere with it and disrupt it. Communicating by a screen can disrupt it. It comes about through biological and social cues we share. It is through eye gaze: breaking someone's gaze, coming back, breaking gaze and coming back. It is the tone of voice. It is visual cues, and smell is also an enormous part of that social cueing. The cells might be doing something but the message has to pass between two people in a way, and it's not magic.
We are now learning and understanding what causes two people, two brains, to synchronise and to start dancing together, and what disrupts that synchrony–and then, what can bring it back together again.
There are so many amazing studies in the book. Is there one in particular that you found particularly fascinating?
Some research looked at how two generations of bodies and brains are impacted by pregnancy and motherhood: the children and the mother.
Most people are very familiar with the concept of baby blues after birth, but not many know about hypervigilance. Which is a real kind of anxiety that dials up the nervous system, especially for first time parents. And I talk about this a few different times during the book, because I was really struck by one of the studies that was done on this.
The study looked at how our minds make meaning of physiological signals. Can you imagine that mother nature has a purpose for us being hypervigilant when our first baby comes along? We're new to parenting, and we have to keep this little human alive. You don't want to forget about it, you need to be focused on it. So there's a purpose.
But the way we seem to make meaning of it, is to catastrophise something going wrong. We have intrusive thoughts that are common amongst mothers. Thoughts of babies falling downstairs and out windows are so universal, and I was quite surprised by that because I thought that was just me.
With my first son, we lived in a second-floor apartment and had a balcony. I didn't even want to go into the room with the doors leading out into the balcony while holding him, because I was convinced he would somehow fall off the balcony if I even went into the room with him.
I had another friend who had a baby around the same time and said she remembered standing at the edge of the carpet near the kitchen tiles in her house. And she was too scared to walk on the tiles because she thought the baby would drop and be smashed onto the tiles.
These fears are incredibly common for the mothers and fathers–the birthing parent and and and other parents. These types of thoughts and postnatal hypervigilance has been shown to tail off by about week seven in healthy parents. But when it persists, we can start seeing it becoming more of a clinical issue. Perhaps anxiety. That's when we need to intervene and start getting help.
I would love other mothers and parents to understand and know what's normal.
Everyone's busy telling women to expect to forget, or expect to feel sad, but perhaps they should be told to expect to have panicky thoughts and feelings. And perhaps you need a psychologist if they persist and start to interfere with your ability to live everyday life.
And I think this hypervigilance is tied to our expectations of maternal instinct and how we should feel when we first hold our baby in our arms.
I surveyed all the mothers and parents in my book and said: what does maternal instinct mean for you? People's descriptions of the meaning of "maternal instinct" depended very much on the experiences they had.
I felt instant love and connection, like I'd known him my whole life. Other people I spoke to felt nothing and felt guilty that they felt nothing. Other women felt fear and panic. That's the opposite to what we think we should be feeling. But that complete range is very normal.
Let's jump to the teenagers. I have a friend who insists she's more forgetful now with teenagers than they ever were with babies, and I don't know if it's right to say, but you kind of rally against this idea in your book.
Well, women say they feel forgetful, but we're not picking up clinical forgetfulness in the research lab. When we are inviting them to a research lab where it's calm, there are no children and they're having a hot cup of tea and doing cognitive testing: the women aren't testing poorly. They're testing normally.
So this word women are using to describe their experience of forgetfulness is not a neurological issue. Memory depends on attention.
What's actually happening is that you've got 10,000 things going on because you're a "super mum" who can do everything. There's nothing wrong with your brain. There are just lots of things to remember. My teenage sons can't remember where their belts and ties are almost every day. I have to say, "Where did you take them off last night?" They don't remember. I say, "Where is your blazer?" Etcetera. They can't remember.
There's no reason for them to blame their brain. They just didn't pay attention to where they put them down. There's nothing neurologically deficient about them at their cognitive peaks as teenagers. But women have been primed to blame their brain if they forget one thing instead of thinking: maybe there's just a lot going on and I can't do it all.
Yeah. I feel women often take a lot on. Sometimes it's out of their control, but sometimes it's in their control. What happens in our brains when we forget things? Is our brain reprioritising?
Well, if you've got this newborn you're vigilantly caring for, your brain is reprioritised because there is a real reason to be solely focused 24/7. But as they grow up, priorities change. And the information that comes in and is retained, depends on our attention, remember.
Brain scans show that we can't focus on two things simultaneously–we can see this behaviourally too. Instead, we shift focus and it's called task switching. You focus here, and you focus there–back and forth–and your performance in both tasks drops. We can see this in simple tests. It's hard to focus on both simultaneously, so your performance decreases and your stress level rises slightly. A little bit of stress can be good because it will focus us on that task. But we're still task-switching which means we're not paying full attention to just one thing. We really can only monotask.
So, if you've got three kids in three different schools, different activities and uniforms. You've got to outsource some of it onto pen and paper diaries or use resources to enable us to manage that.
Interestingly, I was reading about memory the other day, and once people start going down the track of true dementia and true cognitive degeneration and unhealthy ageing, they're not actually aware that they're forgetting. So again, it's this idea that we're internalising the idea of forgetfulness as a cognitive deficiency–we blame baby brain.
Amazing. What do you hope this book does for women?
I want the conversation to start shifting from the colloquial negative stereotype about our brains, and start shifting to reflect the state of science and what the science is telling us.
I think the word 'matrescence' is a really useful phrase to describe this shift. It's a physical, biological, social, psychological and neurological shift. It's a process. And there are strengths that emerge in that process. Our brains become pro-social. We're tuning into this baby and there's an upside for these changes because that's how evolution works in terms of biological outcomes: it's usually what we call adaptive. As I say, mother nature usually has a good reason for this.
Thank you so much for chatting on the lunch lady podcast.
You're so welcome. Thank you.