What Happens to Your Brain During Pregnancy?

Most of the things that we learn about during pregnancy are focused on the physical changes to the body.  And when it comes to hypnobirthing we are often focused on just on birth. I'm not!  With my work I like to explore how we use mindset tools like hypnosis, mindfulness and meditation during pregnancy, and beyond, to optimise well-being for mother and baby and support changes in the brain and body. So when I heard about some extraordinary new research which explored changes that occur in the brain during pregnancy I was really excited. 

Of course we all know this instinctively 😉...but it's good to have the research! 

A team of researchers at the University of California, Santa Barbara, led by Professor Emily Jacobs, has  uncovered some fascinating insights: pregnancy doesn’t just transform the body, it 'remodels' the brain in ways we’re only starting to understand.

Does the Brain Change During Pregnancy?
Professor Jacobs and her team, including lead researcher Laura Pritschet, wanted to explore what happens to the brain during pregnancy, something that hasn’t been studied in this level of detail before. Using advanced brain imaging, they tracked a first-time mum’s brain throughout her pregnancy and for two years afterwards.

The researchers found there are some big changes going on in the pregnant brain. The first thing they noticed was that grey matter (the tissue in the brain involved in decision-making, memory, and thinking) decreased in the volume.

Now, before you worry, the researchers were quick to explain that this reduction in grey matter isn’t necessarily a bad thing. It’s more like the brain is becoming streamlined, a bit like it does during adolescence. In fact, they think the brain might be refining itself to get ready for the demands of motherhood.

This is similar to what is known as pruning, it's the brain deciding what it needs in order to optimise its wellbeing at the next stage of life, and increases its ability to respond to the demands of parenting. 

What’s Happening Inside the Brain?
It wasn’t just grey matter that showed changes. The researchers also noticed an increase in white matter, which is deeper in the brain and helps different regions communicate with one another. Interestingly, this increase in white matter peaked during the second trimester and then returned to normal levels by the time the baby was born.  

This was a surprising discovery, as it had never been captured before in brain scans that only looked at pre- and post-pregnancy changes. What this tells us is that the brain is constantly shifting and adapting throughout pregnancy in ways we don't fully understand.

When I hear things like this it just blows me away.  You are often taught to doubt yourself during pregnancy, about whether you can birth, whether your body is capable of making the adjustments and changes it needs to (which it does without you thinking about it). But on top of that your brain is doing an incredible job of organising itself for the next chapter in your life. 

When people talk of baby brain it's related to this. Think of it as a total reorganisation or your home, maybe moving the rooms around, the furniture in different places, things moved to different cupboards and drawers to make it easier for the stage of life you are at. At first it takes a little time to get used to the new layout, and you may go to one room expecting to find something, when you've moved it to another room. But soon the new layout starts to settle in in, you find your way around and it suits you and your family a lot more. 

This, this is what your brain is doing as well.  It's is a marvel. 

So, What Does This Mean for Mums?
If you’re expecting a baby, this research is reassuring. It shows that your brain is not just dealing with the physical and emotional demands of pregnancy—  it’s adapting to better prepare you for the journey of motherhood. These changes may be part of how your brain gets ready to respond to your baby’s needs and cope with the challenges ahead.  It helps you to recognise your baby's cues for example. 

The study also challenges some of the outdated stereotypes around pregnancy. For a long time, pregnant women have been viewed as fragile or overly emotional, but this research paints a very different picture. Laura Pritschet, one of the lead authors, hopes the findings will help debunk these old myths, showing that pregnancy is a time when the brain is actively adapting and becoming more specialised.

Why Is This Important?
This study has important implications beyond just understanding pregnancy. It could also have a significant impact on how we think about maternal mental health. Around 1 in 5 women experience postnatal depression, but early detection can be difficult. By understanding how the brain changes during and after pregnancy, researchers hope they’ll be able to spot potential warning signs earlier and provide better support for new mums.

My second book Mindful Mamma is about supporting these changes with practical tools that complement these changes in the brain. 

And what's so exciting is that this is just the beginning. The researchers have already started a follow-up project, called the Maternal Brain Project, where they’ll be studying more women — both in the US and internationally. Their goal is to better understand how these brain changes might relate to mental health, immune function, and even how the brain ages over time.

Pregnancy is often seen as a time of growth — a growing baby, a growing family. But as this new research shows, it’s also a time of growth and change in the brain. We’re just starting to scratch the surface of understanding how pregnancy affects the brain, but this study is an exciting step in the right direction.

So, the next time someone mentions ‘pregnancy brain,’ you can tell them it’s not about forgetfulness or being scatter-brained. It’s about your brain preparing for the incredible journey of parenthood — and that’s something to be proud of. 

Further reading

Neuroanatomical changes observed over the course of a human pregnancy. 
Laura Pritschet, Caitlin M. Taylor, Daniela Cossio, Joshua Faskowitz, Tyler Santander, Daniel A. Handwerker, Hannah Grotzinger, Evan Layher, Elizabeth R. Chrastil & Emily G. Jacobs. 
Nature Neuroscience (2024). https://doi.org/10.1038/s41593-024-01741-0