Scientists shed light on the many ways women's brains change during pregnancy

Scientists have analysed a woman's brain throughout pregnancy to offer the first detailed map of one during gestation.

The research followed only one first-time mother but it kicks off a large, international research project aiming to scan the brains of hundreds of women.

"We wanted to look at the trajectory of brain changes specifically within the gestational window," Laura Pritschet, lead author of the study from the University of California, Santa Barbara, said in a statement.

The authors hope the research could one day provide clues about disorders like postpartum depression as well.

How was the brain studied during pregnancy?

The team began following Liz Chrastil, who works at the University of California, Irvine, in the US shortly before she became pregnant through in vitro fertilisation (IVF).

During the pregnancy and for two years after she gave birth, they continued doing MRI brain scans and drawing blood to observe how her brain changed.

"It’s been a very long journey," said Chrastil, co-author of the paper published on Monday in Nature Neuroscience.

"We did 26 scans before, during and after pregnancy" and found "some really remarkable things," she said.

The team found that more than 80 per cent of the regions studied had reductions in the volume of gray matter, where thinking takes place.

This is an average of about 4 per cent of the brain, nearly identical to a reduction that happens during puberty. While less grey matter may sound bad, researchers said it likely reflects the fine-tuning of networks of interconnected nerve cells called "neural circuits" to prepare for a new phase of life.

"Previous studies had taken snapshots of the brain before and after pregnancy, but we’ve never witnessed the brain in the midst of this metamorphosis," said co-author Emily Jacobs of the University of California, Santa Barbara.

Unlike past studies, this one focused on many inner regions of the brain as well as the cerebral cortex, the outermost layer, said Joseph Lonstein, a professor of neuroscience and psychology at Michigan State University who was not involved in the research.

It's "a good first step to understanding much more about whole-brain changes that could be possible in a woman across pregnancy and postpartum," he said.

Women's health 'historically ignored'

Research in animals has linked some brain changes with qualities that could be helpful when caring for an infant.

While the new study doesn’t address what the changes mean in terms of human behaviour, Lonstein pointed out that it describes changes in brain areas involved in social cognition, or how people interact with others and understand their thoughts and feelings, for example.

Eventually, the researchers hope scientists can use data from a large number of women for things like predicting postpartum depression before it happens.

"There is so much about the neurobiology of pregnancy that we don’t understand yet, and it’s not because women are too complicated. It’s not because pregnancy is some Gordian knot," Jacobs said.

"It’s a byproduct of the fact that biomedical sciences have historically ignored women’s health".

The researchers have partners in Spain and are moving forward with the larger Maternal Brain Project, which is supported by the Ann S Bowers Women’s Brain Health Initiative and the Chan Zuckerberg Initiative.