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Ask a group of mothers whether having a baby changed them, and many will say yes without hesitating. They notice the world differently. They pick up on a cry from another room, a shift in someone’s mood, a small sign that something isn’t right.
For a long time, that was treated as a figure of speech. Brain scans now suggest it may be literal. A first pregnancy appears to physically reshape parts of a woman’s brain, and those changes don’t quickly disappear.
Scanning brains before and after pregnancy
Most brain research on mothers has looked at women only after they’ve given birth, which makes it hard to know what changed. A team led by Elseline Hoekzema, then at the Autonomous University of Barcelona, took a different approach.
The researchers scanned the brains of women who were planning to get pregnant for the first time, then scanned them again after they’d had their babies. They did the same with women who didn’t become pregnant, and with first-time fathers. The project ran for more than five years, and the results were published in Nature Neuroscience in 2017.
What changed
In the 25 first-time mothers, pregnancy was followed by clear reductions in gray matter volume in specific brain regions. Gray matter contains the cell bodies of neurons and the connections between them.
The changes weren’t scattered at random. They clustered in areas of the frontal, temporal and midline cortex that closely matched what’s known as the “theory of mind” network. This network helps us understand what other people are thinking and feeling, the skill psychologists call social cognition. It includes parts of the cingulate cortex along the brain’s midline.
The changes were so consistent that a computer program could tell, from brain scans alone, which women had been pregnant. The fathers and the women who hadn’t been pregnant showed no similar pattern.
Smaller doesn’t mean worse
Losing gray matter can sound alarming, but the researchers stressed that it isn’t necessarily a bad thing. The brain also loses gray matter during adolescence, as it prunes weak connections and strengthens the ones that get used most. That process makes networks more efficient and specialized.
Hoekzema has suggested pregnancy may involve something similar. In the study, the mothers showed no changes in memory or other thinking skills. The reshaping seems to be fine-tuning rather than damage.
Linked to the bond with the baby
After the babies were born, the researchers showed mothers photos of their own infants and of other babies while scanning their brains. The regions that had changed during pregnancy overlapped strongly with the areas that responded most to their own baby.
The amount of change also predicted how strongly the mothers felt attached to their babies after birth, based on a standard questionnaire. That suggests the brain may be preparing for one of the hardest jobs of early motherhood, reading the needs of a baby who can’t yet speak.
Hormones are the likely driver. Pregnancy brings huge surges in estrogen, progesterone and other hormones, and the fathers, who didn’t experience those surges, didn’t show the same brain changes.
Two years later, and beyond
When the researchers scanned the mothers again about two years after giving birth, most of the gray matter reductions were still there. The main exception was part of the hippocampus, a region important for memory, which showed some recovery.
A less-reported follow-up went further. In 2021, Magdalena Martínez-García, Susanna Carmona and colleagues, including Hoekzema, scanned a smaller group of the women about six years after they gave birth. Most of the pregnancy-related reductions were still present, and the scans could still identify which women had been pregnant with over 90% accuracy. The brain changes at six years were also linked to measures of mother-to-child attachment.
That later study was small, with only seven mothers and five comparison women at the six-year mark, so its results need confirming. But it raises the possibility that some changes from a first pregnancy are permanent.
What it means for mothers
The research doesn’t mean every mother’s brain changes in exactly the same way, or that women who haven’t had children are less socially skilled. It also only looked at first pregnancies, so it’s not yet clear what happens with a second or third child.
But it does support what many women describe. Becoming a mother isn’t just a change in routine or identity. For many women, it appears to come with a lasting rewiring of the brain’s social circuits, one that may help them tune into the people who depend on them most.
