Please forgive me if you introduce yourself and I forget your name before we've finished shaking hands. Or if I have an appointment with your business at 1 p.m. Wednesday and I show up at 1 p.m. Tuesday. (Seriously, both happened in the last week. At least I was early for the appointment rather than late!) You see, I had a baby within the last two years, and while I've long joked that having kids has turned my brain into mush, it turns out I wasn't kidding. "Baby brain" is real.
A 2016 study published in the journal Nature Neuroscience found that pregnancy leads to changes in the brain structure that can last for two years. The study, which was the first to look at the effects of pregnancy and childbirth on the human brain, found that the amount of gray matter decreases in areas that process and respond to social signals. The hippocampus, which is key for memory, also lost volume. And the more changes in a woman's brain, the higher the level of emotional attachment to the baby, according to the study.
Researchers used MRI scans to examine the brains of 25 women who had never given birth. They conducted scans both before they got pregnant and again a few weeks to a few months after they gave birth. The team of scientists also scanned 19 first-time fathers, 17 men without children and 20 women without children who did not become pregnant during the study. The scans showed consistent loss of gray matter among all the women who had been pregnant — the findings were so consistent, in fact, that a computer could predict, with total accuracy, whether or not a woman had been pregnant simply by looking at the MRI.
Two years later, the women who had children returned for MRI scans, which showed that the matter loss remained, except in the hippocampus, which regained volume. It's worth noting that the results were the same for women regardless of the baby's gender or whether they conceived naturally or through IVF.
Now, a new follow-up study from the same researchers at universities in Spain and the Netherlands and published in the same journal confirms those findings. The 2017 study adds that the loss of matter occurs mainly in the front and temporal lobes, which are responsible for several things including social awareness and understanding people's feelings. This gray matter loss helps mothers bond more with their infants; in fact, the bigger the matter loss, the stronger the mother-child bond, the study found.
So while new mothers' brains shrink, they become stronger and more efficient in other ways. They're better prepared to interpret a baby's non-verbal cues and spot threats in their surroundings.
It's not that we're 'dumb'
Pregnant women and moms of young kids have often complained of forgetfulness or a lack of focus, but that's usually attributed to the physical discomfort, stress and lack of sleep that comes with having and raising children. After all, who can remember where they put their keys or what exit to take off the highway while functioning on 90 minutes of sleep? But while stress and sleep deprivation definitely don't help, they're also not solely responsible.
“We certainly don’t want to put a message out there along the lines of ‘pregnancy makes you lose your brain,’” the 2016 study's lead author Elseline Hoekzema, a neuroscientist at Leiden University the Netherlands and the pregnant mother of a 2-year-old, told Science Magazine. “Gray matter volume loss can also represent a beneficial process of maturation or specialization.”
How can we possibly benefit from decreased brain matter? Well, as the New York Times reports, hormone surges in pregnancy might cause “pruning or cellular adaptation that is helpful," streamlining certain brain areas to be more efficient at mothering skills “from nurturing to extra vigilance to teaching," according to Paul Thompson, a neuroscientist at the University of Southern California.
So the bad news is that we really are losing our minds. But the good news is that we're better mothers for it.
Editor's note: This story has been updated with new information since it was originally published in December 2016.