The study, carried out over a year by scientists at Royal Holloway, University of London, found that pregnant women use the right side of the brain, which is dominant in processing emotion, more than new mothers do when they look at facial expressions.
Researchers examined the neuropsychological activity of 19 pregnant women within their final trimester and 20 new mothers within 20 weeks of giving birth using the chimeric faces test. The test involved showing the women images made of one half of a neutral face combined with one half of an emotive face to see which side of the brain was dominant in processing emotions.
While there was no difference between the two groups when registering negative emotion, pregnant women showed a ‘significantly higher’ use of the right brain hemisphere than the new mothers when registering positive emotions, the study said.
Lead researcher Dr Victoria Bourne from the Department of Psychology at Royal Holloway, who will present the study at the British Psychological Society’s annual conference today, said the heightened use of the right side of the brain during the last three months of pregnancy, normalising again after birth, gave an insight into the ‘baby brain’ phenomenon, which makes women more sensitive during the child-bearing process.
Dr Bourne said, ‘The results suggest that during pregnancy, there are changes in how the brain processes facial emotions that ensure that mothers are neurologically prepared to bond with their babies at birth.
‘We know from previous research that pregnant women and new mothers are more sensitive to emotional expressions, particularly when looking at babies’ faces. We also know that new mothers who demonstrate symptoms of post-natal depression sometimes interpret their baby’s emotional expressions as more negative than they really are.
‘Discovering the neuropsychological processes that may underpin these changes is a key step towards understanding how they might influence a mother’s bonding with her baby.’
The research team plans to extend the work to compare the findings to a control group of women who are neither pregnant nor new mothers, and to further investigate the changing location of emotional control in the brain throughout pregnancy and childbirth.