Pregnancy Changes The Mother's Brain

A new study explores, for the first time, the impact of pregnancy on the structure of the mother’s brain.

Researchers at the Universitat Autonoma de Barcelona (UAB) discovered that pregnancy involves long-lasting changes — at least for two years post-partum — in the morphology of a woman’s brain.

Using magnetic resonance imaging, the scientists found that after a first pregnancy, the brains of women show significant reductions in grey matter in regions associated with social cognition.

The researchers believe that such changes correspond to an adaptive process of functional specialization towards motherhood.

“These changes may reflect, at least in part, a mechanism of synaptic pruning, which also takes place in adolescence, where weak synapses are eliminated, giving way to more efficient and specialized neural networks,” said Elseline Hoekzema, co-lead author of the study.

According to Erika Barba, the other co-lead author, “these changes concern brain areas associated with functions necessary to manage the challenges of motherhood.”

In fact, researchers found that the areas with grey matter reductions overlapped with brain regions activated during a functional neuroimaging session in which the mothers of the study watched images of their own babies.

For the study, researchers compared magnetic resonance images of 25 first-time mothers before and after their pregnancy, of 19 male partners, and a control group of 20 women who had never been pregnant and 17 male partners. They gathered information about the participants over five years and four months.

The results of the research, directed by Òscar Vilarroya and Susanna Carmona, demonstrated a symmetrical reduction in the volume of grey matter in the medial frontal and posterior cortex line, as well as in specific sections of, mainly, prefrontal and temporal cortex in pregnant women.

“These areas correspond to a great extent with a network associated with processes involved in social cognition and self-focused processing,” said Carmona.

The researchers’ analyses of the scans determined with great reliability whether a woman in the study had been pregnant depending on the changes in the brain structure. The researchers note they were even able to predict the mother’s attachment to her baby in the postpartum period based on these brain changes.

The study took into account variations in both women who had undergone fertility treatments and women who had become pregnant naturally, and the reductions in grey matter were practically identical in both groups.

Researchers added they did not observe any changes in memory or other cognitive functions during the pregnancies and therefore believe that the loss of grey matter does not imply any cognitive deficits.

“The findings point to an adaptive process related to the benefits of better detecting the needs of the child, such as identifying the newborn’s emotional state,”  Vilarroya explained. “Moreover, they provide primary clues regarding the neural basis of motherhood, perinatal mental health, and brain plasticity in general.”

The study was published in Nature Neuroscience.

Source: Universitat Autonoma de Barcelona
Photo: Brain regions with volume changes after pregnancy. Credit: Oscar Vilarroya.