How the brain changes during pregnancy

So many things change for a woman during pregnancy – and one of them could be her brain.

New research suggests that "mommy brain" could be "a real thing", said The Washington Post, but the process is quite at odds with the "pop culture conception" of young mothers becoming "cognitively fuzzy and absent-minded".

So what are the changes that occur, why do they happen and what does this discovery mean?

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'Sweeping reorganisation'

The brain undergoes a "sweeping reorganisation" when a woman is expecting a baby, said The Guardian, and few areas are untouched by the process. Regular MRI scans from before conception until two years after childbirth revealed "widespread reorganisation" in the mother's brain, said the paper.

Some regions of the brain, "especially those involved in social and emotional processing", got smaller, possibly "undergoing a fine-tuning process in preparation for parenting", said The New York Times.

People can "bristle" when they hear that "grey matter volume decreases in pregnancy", said Professor Emily Jacobs, a researcher on the study from the University of California, Santa Barbara. But this change "probably reflects the fine tuning of neural circuits, not unlike the cortical thinning that happens during puberty".

Jacobs compared this process to Michelangelo's masterpiece, "David". "You start off with this chunk of marble, and you chip away – that pruning can reveal the underlying beauty," she said.

While grey matter decreases, there were significant increases in white matter, the nerve fibres that connect neurons and help different brain regions communicate. All of this remodelling, or neuroplasticity, took place across the brain, at three times the rate seen in eight non-pregnant women who also had their brains scanned over the same period.

Maternal fine-tuning

This "probably enables the onset of certain maternal behaviours", said New Scientist. This has already been seen in rodents, where increases in steroid hormones during pregnancy "trigger brain changes" that "enhance the mother's sensitivity to smells and sounds from her pups".

A similar process may be happening in humans, according to several studies. One team found that the scale of change in grey matter volume corresponds with the extent of parental attachment.

'Linchpin of human existence'

Pregnancy is a "linchpin of human existence", said The Washington Post, but the maternal brain has been "understudied and underappreciated" until now. Several experts have welcomed the progress – Gina Rippon, from Aston University in Birmingham, told The Guardian it was "a truly heroic" study.

Some of the brain developments were still present two years after childbirth, "hinting at cellular changes in the organ", which could be permanent. Therefore, said Dr Elizabeth Chrastil, from the University of California, Irvine, the study "really opens up more questions than it answers" and "we're really just starting to scratch the surface".

New studies mean that deeper scratching is already under way. A greater understanding of the brain's "remodelling" could explain several pregnancy-related behaviours, said New Scientist, as well as helping people at risk of mental health conditions.

A new series of scans is now being collected from other pregnant women to explore the dangers of postnatal depression and the connection between pre-eclampsia and dementia. Scientists also want to understand why pregnancy can reduce migraines and indications of multiple sclerosis.