Current Issue #488

Debunking the Baby Brain Myth

Debunking the Baby Brain Myth

Pregnancy does result in physical changes in a woman’s brain, but those changes might be more likely to give you interpersonal superpowers than ‘baby brain’, says Dr Jessica L Paterson.

You may have heard the term ‘baby brain’ being used to describe the forgetfulness and difficulty concentrating that sometimes accompanies pregnancy. The term is so widespread, and supported by so much anecdotal evidence, that you would probably be surprised to hear that until recently, there was limited scientific evidence to support the existence of actual physical changes in the brains of pregnant women.

While one study in 1997 showed that parts of the female brain shrink during pregnancy, it wasn’t until early this year that research published in Nature Neuroscience showed that these reductions occur in grey matter volume, particularly in areas responsible for social cognition. And not just any kind of social cognition, but particularly in the areas responsible for ‘theory of mind’, which is the skill that allows us to think about what is happening in someone else’s mind.

Reduced grey matter sounds like it would be associated with negative change — but researchers think maybe the pregnant brain is ‘pruning’. Pruning is when the brain becomes more efficient at a certain task by removing unnecessary neural networks. This apparent pruning of grey matter was associated with stronger maternal-infant attachment, leading the authors to conclude that pregnancy-related changes in brain structure are adaptive, positive, and facilitate effective communication with the baby. Myth, busted.

There is also evidence that the pregnant brain acquires skills akin to interpersonal superpowers. One hundred and fifteen heterosexual pregnant women and 857 heterosexual not-pregnant women were shown pairs of male faces manipulated so they appeared either ‘healthy’ or ‘unhealthy’. The women then had to choose the face they preferred, and indicate how much they preferred that face. Pregnant women were more likely than non-pregnant women to choose the ‘healthy’ faces.

The researchers suspect that this increase in perception was probably a result of the high levels of progesterone associated with pregnancy. Progesterone is the hormone that prepares the female body for pregnancy after ovulation, helps to stop the body rejecting a fertilised egg, and primes the breasts for milk production. High levels of progesterone also suppress the immune system. An improved ability to tell if someone is unhealthy on sight may protect the woman, and their unborn child, from being infected with an illness. This, of course, is one of many superpowers that women possess because we are all beautiful, sacred unicorns.


Another startling cognitive ability that pregnant women develop? The ability to detect threat or aggression in the faces of strangers. In a study at the University of Bristol, pregnant women were significantly better at detecting and labelling fear, anger, and disgust in strangers’ faces in late pregnancy, compared to early pregnancy. What changes occur during pregnancy that could explain this increase in threat perception? Hormonal hero of the day progesterone, of course. Progesterone is elevated throughout pregnancy, and increases dramatically in late pregnancy. The researchers concluded that this increased ability to detect negative emotion in others could help pregnant women avoid individuals who may harm them or their baby.

So, there are many reasons not to mess with a pregnant woman including, but not limited to, the multitude of neural changes that essentially make them superhuman, mind-reading, germ- and threat-detecting RoboCops.

Could long-held myths about ‘baby brain’ be another way of holding women down because men are terrified of the amazing things that women are able to do that they never will, like grow an entirely new human? Maybe anecdotal reports of memory loss and difficulty concentrating during pregnancy are the result of a Golem effect? That is, you’re expected to experience some cognitive decline, so you do. Or could it be the flow-on effects of the sleep loss that so often starts with the realisation that you’re pregnant and tends to worsen as you become big enough to store another person in your belly, all while trying to sleep only on your left side because you read THAT IS WHAT IS BEST FOR THE BABY*.

The message? Baby brain is nothing to fear. In fact, there’s good reason to think that it exists to bestow benefits on both mother and baby. So, go forth pregnant women — may your bellies expand, and your grey matter shrink!

*Scientific evidence actually supports this, particularly during the later stages of pregnancy, when sleeping supine has also been associated with later risk of
SIDS (Sudden Infant Death Syndrome). Sleeping on the left side keeps pressure off the vena cava — the vein that carries blood from your lower extremities to your heart. Pretty important.

Dr Jessica L Paterson, Senior Research Fellow, CQUniversity, Appleton Institute

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