How pregnancy reshapes the brain throughout life

A Mother’s Brain: The New Science of the Neuro-Maternal Revolution Susana Carmona MIT Press (2026)

When I acquired a copy of the book A Mother’s Brain by neuroscientist Susana Carmona, I thought: at last, a book about what happens to your brain during pregnancy. I recalled how I’d realized in 1997, when I was a young assistant professor, soon after giving birth to my first child, that books for expectant or new parents were light on what happens to the brain. As a neuroscientist, I was curious. What was going on with my brain?

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Another observation that I had was how jarring it was to go from having so much attention being paid to me when I was pregnant — including intrusive attention about what I was consuming and unwanted hands on my belly — to the utter lack of attention on me after my baby was born. All of the attention went from pregnant me to the baby. Fair enough, babies can be cute, but what about the mum? What was happening to me? Clearly things in my brain were different, but there was little in the scientific literature to tell me what was happening — which is one of the big reasons I started to work in this area of neuroscience.

My first study on this topic (L. A. Galea et al. Horm. Behav. 37, 86–95; 2000), was about memory and changes in the volume of the hippocampus, a region of the brain, throughout pregnancy. Fast forward two years to me being pregnant with my second child, and I could not for the life of me find where I had parked my car at the end of the day. It was not unusual to find me crying in the stairwell of a ten-storey car park because I was about to be late to pick up kid number one from childcare.

In my experience, mums are often told that our bodies will ‘bounce back’ after pregnancy. But work from Carmona and others now suggests that pregnancy can leave lasting signatures on the brain and body. This will probably not shock any parent, particularly the one who gave birth.

A remarkable transition

A Mother’s Brain is, in many ways, an ode to the remarkable ‘plasticity’ or adaptability of the brain and body during and after pregnancy. Gestation requires adaptations across almost every physiological system, and Carmona describes these changes to the cardiovascular, immune and circulatory systems exceptionally well. The book also details the remarkable role of the placenta in orchestrating many of these adaptations. When considering this physiological transformation, it’s no surprise that pregnancy also leaves a signature on the brain.

Carmona conveys her palpable love of being a mother while recognizing that motherhood is not universally joyful. I agree strongly with Carmona’s contention that people need to be truthful with parents-to-be. The experience isn’t always positive. Some people will experience mental-health challenges during this period, possibly for the first time.

It is important that they seek — and receive — the support that they need. Care during pregnancy and in the postpartum period must attend to mental as well as physical health, and timely access to effective treatments, including talk therapy, should be standard. The repercussions of not receiving enough support can be tragic.

The book is at its best when Carmona conveys just how biologically extraordinary pregnancy is. For example, she describes how cells from a baby can linger in the bodies of people who have been pregnant, sometimes for decades, yet it is still not known how these cells contribute to long-term health. Carmona also takes the reader through the genesis of her own research questions and the paths they took from idea to publication, interspersing the science with anecdotes from her life and pregnancies.

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Yet, I found myself wishing that Carmona had gone into more detail about another part of this story: how difficult it has been to convince the scientific community that pregnancy’s effects on the brain are worth studying. Carmona’s first landmark paper on this topic (E. Hoekzema et al. Nature Neurosci. 20, 287–296; 2017) did not have an easy path to publication. I know this first-hand. I was one of the reviewers who argued with the editors about the importance and novelty of the work.

There are many hidden obstacles to publishing research on women’s health, even though the paucity of existing research might suggest the opposite, given that new findings are paramount for getting your work accepted. Many researchers in the field need to justify that their findings are worth publishing. I would have welcomed more exploration of that resistance and why questions concerning pregnancy and the brain are often overlooked.

Discussion of what these pregnancy-related brain changes mean is also important. These are natural adaptations. For example, people often experience a reduction in brain volume during gestation. But this is not necessarily a bad thing, just as an increase is not necessarily good. Different brain regions and measures (such as volume and connectivity) change in various ways during pregnancy and in the postpartum period, and the overall effects can be confusing to piece together. But such distinctions are, as Carmona points out, important for a public audience for whom headlines about a ‘shrinking brain’ can sound alarming.

Parallels with other species

Consider the hippocampus. A Mother’s Brain describes this region but pays relatively little attention to the striking parallels between human findings and decades of work in other mammals. These studies have shown that rodents experience pregnancy-related and postpartum changes to cognition, to the structure of the hippocampus and to the creation of nerve cells in the brain. In rats, the production of neurons decreases during pregnancy and the early postpartum period, with subtle variations between first and second pregnancies. There are also later differences between foster mothers and birthing mothers in terms of brain-cell creation in the hippocampus and memory that remain to be explained.

In the long term, beyond the postpartum period, reproductive experience improves memory and the plasticity of the hippocampus because it results in changes to nerve-cell quantity and connections throughout life. That paradox — decreases in one measure alongside improved function in others — is why interpreting pregnancy-related brain changes requires more than asking whether a measure went up or down.