SOME pregnant women complain that their brains have gone on leave
鈥攖hey find it difficult to concentrate, and have poor memories. Now, an
explanation may be at hand: a group of anaesthetists and radiologists believe
that women鈥檚 brains shrink during late pregnancy and take up to six months to
regain their full size.
Anita Holdcroft, the anaesthetist leading the team, based at the Royal
Postgraduate Medical School in London, believes that this unexpected observation
could be linked to the cognitive problems experienced by some pregnant women and
new mothers. 鈥淭hese are very early findings, but it may be that the two features
are linked,鈥� she says.
At a meeting in Sheffield this week, organised by the Physiological Society,
Holdcroft described how the researchers built up three sets of magnetic
resonance images to give three-dimensional pictures of the brains of 10 healthy
women. The first set were taken towards the end of pregnancy, the second 6 to 8
weeks after delivery and the third up to 6 months later. Comparing the images,
Holdcroft and her colleagues found that as the women鈥檚 physiology returned to
the non-pregnant state, their brains increased in size. It is possible that the
women鈥檚 brains were swelling from a normal size, the researchers concede, but
they think it much more likely that the women鈥檚 brains had shrunk during
pregnancy.
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The pituitary gland at the base of the brain鈥攚hich releases a
wide range of hormones, including some responsible for regulating
reproduction鈥攕howed the opposite effect, apparently increasing in size
during pregnancy.
Holdcroft believes that the changes in the brain are more likely to be the
result of changes in the volume of individual cells, rather than changes in the
number of cells in the brain. Her team is now investigating the mechanisms
involved.
The research into brain size and pregnancy started with women who developed
pre-eclampsia, a syndrome involving high blood pressure and fluid build-up that
affects some pregnant women, causing their faces, legs and arms to swell. If
untreated, it can lead to fatal seizures.
鈥淲e assumed that their brains would also swell, but last year we found that
they shrink,鈥� says Holdcroft. The new research suggests that this is not a
symptom of pre-eclampsia, but a normal feature of pregnancy.