I'm a neuroscientist. I scanned my own brain 26 times to see how it changed during pregnancy.

Yahoo

3 days ago

For decades, expectant women have talked about having 'mommy brain' or 'pregnancy brain,' a phenomenon where you're more absent-minded than usual during pregnancy and the postpartum period. But despite this being commonly discussed, scientists haven't really studied it. Liz Chrastil, an associate professor of neurobiology and behavior at the UC Irvine Center for the Neurobiology of Learning & Memory, sought to change that. She had her own brain scanned 26 times before, during and after pregnancy to document the physical changes in a way that had never been done before. Chrastil shares with writer Korin Miller the inspiration behind her research, what it was like to be on the other side of science and what she hopes will happen next.
I'm a researcher who specializes in learning and memory, and I use magnetic resonance imaging (MRI) regularly in my work. But the tables turned, and I ended up becoming the subject of a study of the human brain during pregnancy when I was trying to conceive.
I was inspired by Laura Pritschet, a graduate student working at the University of California, Santa Barbara, under my colleague, Emily Jacobs. Pritschet had recently finished a study on herself on how the menstrual cycle impacts the brain, and it made me think I should do the same during my pregnancy journey in 2019.
I went through in vitro fertilization, so I had a great idea of the timing of my pregnancy. All that was left to do was to track myself, and I did — over 26 MRI scans.
I'm used to doing MRIs quite a bit, given my field. I know that the American College of Obstetricians and Gynecologists says that MRIs are not linked with pregnancy risk and are the imaging techniques of choice when they're needed during pregnancy.
MRI uses a magnet, and there are no injections or radiation. There are no known risks, but we looked at studies of people who had done MRIs during pregnancy for medical reasons, and there were no safety concerns. I did want to be cautious about sound, so we put some foam in the machine as an added precaution to muffle the sound the scanner makes.
After that, I worked with my collaborators to come up with the protocols that would be needed for the scans. It ended up being that I simply made appointments to be in the MRI scanner and to do blood draws as well. I tried to time the blood draws to happen just before the scans so the data would be gathered as close together as possible.
The MRI sessions weren't short. We did about six or seven different scans each time, ultimately taking about 40 minutes each. I did 26 scans overall, which means I spent more than 1,000 minutes in an MRI scanner before, during and after my pregnancy.
During each scan, I had to get set up, be positioned well and just try to get comfortable. Later on in my pregnancy, it was more important just to be comfortable.
I had to lay still and stay awake for one of the scans, so I would just think about whatever I wanted during that time. We made a point to do that scan first, and it usually was over in 10 minutes. After that, I would just rest or fall asleep during the other scans. I usually slept — I was pregnant, after all.
The research on my brain was eventually published in the journal Nature Neuroscience, featuring photos and breakdowns of all of my scans. We saw some noticeable changes to my brain over time.
One big standout was in the volume of gray matter in my brain. Gray matter is a type of tissue that's mostly responsible for processing memory, along with sensory perception, speech and decision-making. The gray matter decreased about 4%, and those changes are pretty permanent. In tracking this, we could see a steady decrease and a slight bounce back in volume, but it never really fully returned. I haven't noticed a change in how I think, though.
We also looked at white matter, which acts as the 'superhighway' in the brain to form big connections. We think of this as the road information travels on. Here, we found an interesting change where the structural integrity of white matter improved and peaked around the second trimester before returning to baseline after my baby was born. Again, I didn't notice a difference in how I thought or felt during this time.
The purpose of the study was to look for changes in the brain during pregnancy. It's 2025, and it's shocking how little we know about some of these things. There were basically no studies on brain changes during pregnancy, so it was up to us to do the research. But we don't know yet what these findings mean.
We don't know if these brain changes are good or not. There is some suggestion that these changes are adaptive, morphing the brain on purpose to help with maternal care. But it could also be a trade-off. The body may be saying, 'We've got other things to do here. Sorry, brain!' and shuttling vital resources away from the brain to other areas. So, we really don't know. Now, we need to find out what all of this means.
General interest in this area of research has opened up, and there's been a very big response in the research community to our work. We're now working with other people and plan to do another round with a bigger sample of 10 to 15 pregnant women. After that, we'll scan hundreds of pregnant women but with fewer time points.
I'm lucky that I had no major issues with postpartum depression, but estimates from the Centers for Disease Control and Prevention show that up to one in eight women do. We're keeping an eye toward postpartum depression with our research and who is most vulnerable. The hope is that we can help to identify how the risks of postpartum depression change during pregnancy along with where, when and how we can help to prevent it.
Ultimately, the big thing is that we actually did the study and asked the questions. This is a huge area of research that has been overlooked — and we're actively trying to change that.