“Baby Brain” - new research proves pregnancy changes women’s brains

Neurological changes in mothers can last for years according to a new study

For decades, “baby brain” has been shorthand for something dismissive: forgetfulness, fuzziness, the brain fog and memory problems during pregnancy and postpartum. It’s a phrase often delivered with a shrug of apology by a mother or worse, a smirk from someone watching a woman struggling.

But a recent study indicates that pregnancy has a profound structural impact on brains and offers new clues into the neurological changes in mums‑to‑be.

Research over the past decade by a group of scientists in Spain and the Netherlands has been mapping those changes in unprecedented detail.

Findings in the largest research to date suggests that grey matter - the nerve-rich part of the brain involved in processing information, emotions and empathy - decreases by an average of nearly 5% during pregnancy.

And scientists working on the Be Mother project say these changes may be beneficial when it comes to caring for newborns.

The brain changes on purpose

Researchers led by Prof Susana Carmona, director of the NeuroMaternal at the laboratory at the Gregorio Marañón Health Research Institute in Madrid, and co-lead with Prof Oscar Vilarroya, scanned the brains of 127 first time pregnant women five times - before, during and after pregnancy - and compared them to scans from 52 women who had never been pregnant.

The results were consistent and striking. Grey matter decreased by nearly 5% in regions of the brain involved in self-awareness, reading others’ emotions and social perception during pregnancy, reaching the lowest point in the final weeks before birth. By six months after birth, grey matter regained volume by around 3.4%. This was seen in all women who took part in the study.

Rather than damage or loss, scientists believe this reduction in grey matter reflects a process known as “pruning”, the brain trimming away unnecessary connections to become more efficient.

“I like to use the metaphor of pruning a tree,” Professor Carmona says. “Some of the branches are cut to make it grow more efficiently.”

Rewiring for connection

The women who showed the most pronounced brain restructuring were also more likely to report stronger bonding with their babies. This suggests something powerful: pregnancy may biologically prepare the brain for connection.

One participant in the study put it plainly: “Rather than becoming dumber, we are becoming more specialised for the job.”

Pregnancy is physically and emotionally demanding. Sleep is disrupted. Energy is ebbing.

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The dominant narrative for decades reduced carrying a baby to inconvenience with mental fog, missed appointments and forgotten names. Which are all real experiences for many expectant mothers.

But these cognitive changes appear to be driven by biology itself, not just the experience of becoming a parent. The transformation seems to be closely tied to pregnancy hormones, especially oestrogen, which rise dramatically and track alongside these neurological shifts.

And the changes don’t simply disappear after birth. While some grey matter returns, traces of this transformation can remain for years, a lasting imprint of matrescence, the transition into motherhood. Other research has shown brain scans alone are able to correctly identify which women had been pregnant even six years after birth, with more than 90% accuracy, proving pregnancy leaves a lasting mark on the brain.

So perhaps the real issue with “baby brain” isn’t that it’s inaccurate but that it’s incomplete. It’s a reprioritisation for new mums to put resilience, perspective, and clarity at the forefront of mind. And pregnant women should no longer be diminished with the turn of phrase, but respected for her transformation, body and mind.

Matrescence - the physical, psychological, and emotional process of becoming a mother - is experienced by millions of women every year, but the lack of research is striking.

Now scientists are beginning to map what happens to the brain during pregnancy. It raises important questions about mental health and how these changes relate to the one in five women who experience depression around the time of birth, support systems, and what it means for health care.

Because if the brain is being reshaped during pregnancy, then the transition to motherhood deserves to be recognised for what it truly is: a major neurological event.