Once a mother, always a mother (just ask your brain).

by Winnie Orchard, PhD student, Turner Institute of Brain and Mental Health and Monash Biomedical Imaging, at Monash University.

Motherhood restructures the brain.

When I tell new mothers I’m a neuroscientist researching brain changes in parenthood, they almost all say something like: “Oh, so you can tell me where my memory went!?”, or, “Yes! Can you tell me what’s going on in there?”, or “Tell me why I have baby brain“.

They agree that their brains have been profoundly altered by the transition to motherhood. They feel it intimately— there has been some fundamental shift. But they are surprised when they find out how little we actually know about these changes, their causes, their purpose, and their time course.

Before a woman gives birth, the extreme hormonal changes of pregnancy trigger a restructuring of the social brain. The change is maintained throughout the postpartum period by the ongoing experience of caregiving.

Pregnancy fine-tunes the brain areas involved in empathy and theory of mind – the ability to understand another person’s thoughts, feelings or needs.

Brain changes during pregnancy support a smooth transition to motherhood.

Mothers who experience these brain changes to a greater degree experience better attachment, more positive feelings towards their babies, and increased maternal self-efficacy (confidence in one’s own parenting ability).

The brain changes of early motherhood support the development of new skills and behaviours.

Parenthood represents a new life stage.

The transition to parenthood is experienced widely throughout the adult population. Parenthood represents a new life stage with different challenges and priorities.

As children grow, the parenting behaviours required to care for them change too. Any parent will tell you new challenges continually arise: nappies and baby bottles are swapped for school lunches and soccer practice. Children’s needs continue to shift for years—even decades—and many parents have to juggle the simultaneous care of multiple children at different ages. Successfully navigating these challenges requires parents to rapidly learn new skills and behaviours on the job.

I actually think “life-stage” is a very good way to think about the motherhood transition. Maybe we should start to think of motherhood as a developmental milestone. The same way we think about childhood, puberty, menopause, and so on.

The transition to motherhood is a sort of ‘second puberty’.

Just like the changes of adolescence prepare our bodies and brains for the responsibilities of adulthood, the changes we see in the pregnant and postpartum brain prepare us for the tasks and responsibilities of motherhood.

The types of brain changes we see across pregnancy and the early postpartum period are very similar to how the brain changes in adolescence. But parenthood research is extremely under-studied compared to infancy, puberty, menopause, and ageing.

Where are all the studies on ‘baby brain’?

When I started researching this area, very few studies looked at women’s brains beyond early parenthood. Most studies on human parenthood are “infant-centric” rather than “parent-centric”. In other words, most studies have used functional magnetic resonance imaging (fMRI) to measure parents’ brain response to infant pictures, movies, or sounds of infant cries – rather than focusing on changes that occur more broadly in the parental brain.

Until now, the time course of these profound changes, which are so important for maternal behaviours, was completely unknown.

• Are the brain changes permanent?
• Do they endure throughout the lifespan or revert back to a pre-pregnancy state after some time?
• If they revert, after how long?
• And what if you have more than one child?

For the last few years, we have been tracking down the answers to some of these questions.

The brain changes of motherhood last a lifetime.

Our research has investigated the structure and function of the maternal brain in late life. We are curious about what motherhood means for cognition as women age.

Motherhood impacts the brains of women in their 70s and 80s – three or more decades after they became mothers!  

Elderly women with more children have thicker grey matter in the parahippocampal gyrus, a brain region important for memory. This is particularly exciting because we also found that mothers with more children had better verbal memory (i.e. remembering lists of words).

We also found a relationship between the number of children a woman mothered and brain function.

We saw the more children an elderly woman had, the “younger” her patterns of brain function. This suggests motherhood confers a neuroprotective effect on brain function in late life. In these women, the pattern of brain activity trended in the opposite direction to what we’d expect to see during ageing.

The more children a woman has, the “younger” her patterns of brain function.

We observed a ‘younger’ pattern across brain structure, function and cognition. All of which suggest motherhood is neuroprotective for the ageing maternal brain.

Life-long benefits of a complex environment

We attribute these neuroprotective effects to the ongoing demands of motherhood.

We know from studies in people and in rodents that experiencing a complex novel environment results in a brain that is healthier, more flexible, and more resilient to ageing. It seems that complexity is good for the brain.

The experience of motherhood provides a lifetime of this environmental complexity. Think about getting a baby to go to sleep – just when you think you’ve got it all figured out, the baby’s sleep cycle changes and that particular tactic doesn’t work anymore – you have to stay flexible and adapt to a growing and changing child with different challenges and needs at each developmental stage.

The experience of motherhood can be thought of as “brain-training” – keeping us on our toes well into late-life.

It is still far too soon to say that motherhood is outright beneficial for the ageing human brain. However, our findings suggest motherhood reshapes the brain, these changes last a lifetime and are beneficial.

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At the time of writing, Dr Winnie Orchard was PhD Candidate at the Turner Institute of Brain and Mental Health and Monash Biomedical Imaging, at Monash University. As of 2023, Dr Orchard holds a prestigious Kavli post-doc fellowship and is continuing her research into the maternal brain at the Before and After Baby Lab at Yale University. Her research investigates the structural and functional brain changes associated with parenthood across the lifespan. She has a special interest in how these changes relate to parental cognition and mental health in the postpartum period.

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