New scans reveal how the brain re-organises during pregnancy
Changes that sweep the the human brain during pregnancy have been documented for the first time, using precise MRI scans.
Scientists conducted 26 brain scans on and took blood samples from a healthy 38-year-old woman, Dr Elizabeth Chrastil, every week from before conception until two years after the birth, showing how her brain changed, week by week. Some alterations lasted years, while others were only short term.
The work means that researchers should be able to come to a deeper understanding of an expectant mum's brain. More scans are now being conducted on other pregnant women, with the hope to learn more about the risk factors for postnatal depression and why pregnancy can reduce the symptoms of conditions like migraine and multiple sclerosis.
Researchers have previously taken images of pregnant women's brains, but these can miss temporary changes in the brain that go back to normal by the time the woman gives birth. These new scans could help identify important neural signs, like risks for postpartum depression.
Lead author, Laura Pritschet, noted that high levels of hormones oestrogen and progesterone, responsible for blood plasma, immunity and metabolism changes, also reorganise the brain.
What did the scans show?
The brain is made up of grey and white matter, both of which underwent change. Most notable was a steady decline in volume and thickness of grey matter, the part of the brain and spinal cord that handles vital functions like memory, emotions and movement, and which comprises its wrinkly outer surface.
In particular, there was a reduction in areas involved with social cognition. A short-lived spike in brain connectivity also occurred at the end of the second trimester.
There was an increase in white matter, the type of brain tissue located deep in the organ and made up of nerve fibres, and which allows different neural regions to communicate with each other.
The team noted that some changes like the volume and thickness of the cortex – the outer layer of the cerebrum, the largest part of your brain responsible for conscious thoughts and actions – remained altered in the postpartum years, but many other changes returned to pre-pregnancy states.
'The maternal brain undergoes this choreographed change across gestation and we’re finally able to observe the process in real time,' said Professor Emily Jacobs, a researcher on the study at the University of California, Santa Barbara.
She offered reassurance on the reduction in brain tissue: 'Sometimes people bristle when they hear that grey matter volume decreases in pregnancy,' Jacobs said. However, 'this change probably reflects the fine tuning of neural circuits, not unlike the cortical thinning that happens during puberty.'
Gina Rippon, a professor emeritus of cognitive neuro-imaging at Aston University in Birmingham, said it was 'a truly heroic' project. 'The data from this study illustrate just how much we have been missing,' she said.
'This approach will not only help us map maternal neuroplasticity, but also identify markers that indicate risk for postpartum depression, a serious condition that often goes untreated,' she said.
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