Revealed: Why new mothers get ‘baby brain’
Women lose grey matter during pregnancy, a study exploring the “baby brain” phenomenon has found.
Some women experience forgetfulness and cognitive issues during and after pregnancy, but the reasons for this have been little understood.
But scans of a neuroscientist’s brain before, during and after pregnancy revealed 80 per cent of its regions shrunk in size after conception.
Experts say this loss of volume is likely permanent and part of a puberty-like process where the brain is sculpted and fine-tuned by the hormones released by pregnancy.
Dr Elizabeth Chrastil, a co-author of the study and a neuroscientist at the University of California at Irvine, was 38 when she gave birth in May 2020 to a baby boy.
The academic underwent regular scans but the data and findings were only looked at after the study had concluded.
Dr Chrastil’s scans were compared with brain changes observed in eight women who were not pregnant and revealed decreases in cortical volume and thickness. Increased connectivity in the white matter and increases in cerebrospinal fluid were also detected.
Scientists say that some of the results, such as white matter connectivity, were reversed after giving birth, but many are likely permanent alterations.
Dr Emily Jacobs, a study co-author from the University of California at Santa Barbara, said: “Many of these changes seem to be permanent etchings in the brain.”
She added that the brain modifications were comparable with those which happen throughout puberty, when the brain also undergoes a process of rearrangement as well as cortical thinning.
“Loss of brain volume probably isn’t a bad thing,” Dr Jacobs told reporters.
“This change probably reflects the fine-tuning of neural circuits, not unlike the cortical thinning that occurs during puberty. In both cases this process allows the brain to become more specialised.
“Pregnancy probably reflects another wave of cortical refinement. When we looked at the data for the first time, we saw this decrease over time and we were in awe. You can see the sculpting of the brain unfold week by week.”
Dr Chrastil said she had not experienced any “baby brain” symptoms, despite the findings. “I didn’t really experience any of the ‘Mommy brain’ symptoms,” she said. “Science is slow, my son is now four-and-a-half.”
Scientists are now repeating the initial experiment on more women and have gathered similar scans during pregnancy in five other women, with preliminary findings indicating they underwent the same changes.
Research could predict postpartum depression
The scientists say the changes in the brain during pregnancy follow similar patterns as those which affect other hormonal processes, such as the menstrual cycle, but on a much larger scale.
Future work will look at using the detailed scans and findings to understand more about what happens to the brain during pregnancy. The research will also help use the data to help predict which women may be more at risk of developing postpartum depression or preeclampsia.
“One in five women experiences perinatal depression and … early detection remains elusive,” the study authors write in the paper, published in Nature Neuroscience.
“Precision imaging studies could offer clues about an individual’s risk for or resilience to depression before symptom onset, helping clinicians better determine when and how to intervene.
“Precision mapping of the maternal brain lays the groundwork for a greater understanding of the subtle and sweeping structural, functional, behavioural and clinical changes that unfold across pregnancy.
“Such pursuits will advance our basic understanding of the human brain and its remarkable ability to undergo protracted plasticity in adulthood.”