The neurobiology of matrescence

i.e. how your brain changes when you become a mother

During the later stages of pregnancy – particularly during the third trimester, the female brain undergoes a number of changes – the second most significant brain change a person can go through after adolescence (not including childhood!).

This is a very new area of research – the earliest research was in 2002 which identified brain volume changes in a mother, but they had no idea what it meant.

The next time this was studied was in 2016, when three female scientists (who were also mothers) set out to investigate these changes. They used MRI imaging and found there was a decrease in the grey matter of the brain.

The grey matter is responsible for executive tasks – vision, hearing, the processing of memories and emotions, and making decisions. The area of grey matter that they identified specifically were in the regions of social cognition.

These changes however, have no cognitive effect. i.e. they do not impact intelligence! Instead, what they described to happen was a ‘tuning & pruning’ of synapses. It’s essentially a renovation - any old synapses that are no longer used are cleared away, and there is an increase in new synaptic connections. Meaningful information is retained, and information that is no longer required is pruned.

These new connections are mainly in the regions of the brain that play a key role in how we understand and interpret the actions, intentions, and feelings of others. It increases our capacity for empathy and the theory of mind (our ability to predict and interpret the behaviour of others based on our understanding of other’s mental states).

This renovation, or restructuring essentially remodels our brains to prepare us for motherhood.

Like in adolescence, some while coast through these changes, some will be severely affected by it.

Memory issues, forgetfulness, difficulties with recall, losing your keys only to find them later in the freezer..

‘Mum-brain’ or ‘Mumnesia’ is very real, and isn’t it nice to know that there is a very real reason behind it?

The good news is that further studies have found that these changes are not as profound in subsequent pregnancies.

These changes are long lasting however - another study on the maternal brain changes in pregnancy from 2021 showed that these changes can last for up to six years.

There is risk here for the women who are struggling with these changes. Like in adolescence, there is a risk that the fear and negative thinking networks may become deeply ingrained during matrescence, like it can in adolescence.

This can expose mothers to significant mental health issues, which further highlights the need for new mothers requiring a greater level of support than is currently available.

The researchers from the 2016 study included first time fathers in their study as a control group, and they noted no changes to the volume of their grey matter.

This demonstrated that these brain changes occur due to the biological process of pregnancy rather than experience-dependent changes associated with approaching parenthood

These brain changes can result in improved cognitive performance for mothers. It can make them more adaptable and whilst this is relatively very new research, there is some speculation that it can have a neurologically protective effect later on in life.