An intriguing link between a mother’s stress levels during pregnancy and the effect on the brain of her unborn baby is revealed in a new study of children born in Bristol, England.
The research suggests that a woman who suffers anxiety during mid pregnancy is more likely to have a child who shows mixed handedness – neither left nor right handed - and that is associated with a range of conditions such as autism, dyslexia and hyperactivity. .
The findings, published in the medical journal Early Human Development, are based on information collected by the Children of the 90s project based at the University of Bristol.
Professor Vivette Glover from Imperial College in London analysed data on 7,400 mothers and children.
Mothers were asked to report whether, at the age of three a half, their child used the right or left hand for six tasks – drawing, throwing a ball, colouring, holding a toothbrush, using a knife and hitting things.
In the analysis, children who used either hand for two or more tasks were classified as mixed-handed – 21.3 per cent of the boys and 15.4 per cent of the girls.
The results were compared against standard tests of mother’s anxiety at three stages during and after pregnancy.
Previous research with animals had suggested that there is a link between prenatal stress and laterality – our natural preference for using one side of the body.
While handedness is often inherited, it is also believed that it may be affected by conditions in the womb – specifically by increased levels of hormones such as testosterone.
When the results were analysed, Professor Glover found that women who suffered anxiety in the 18th week of pregnancy were more likely to have a child who showed mixed handedness. There was no significant connection with anxiety later in pregnancy or with ante-natal depression.
Professor Glover reports: “These findings show that the connection between antenatal stress and anxiety and atypical laterality observed in animal studies also exists in humans.