Drinking one or two glasses of wine a week during pregnancy does not harm the mental development of the baby and is even linked with an overall improvement in the behaviour of toddlers, a major study found.
Heavy drinking while pregnant carries a high risk of serious health problems to the growing foetus but light drinking – defined as taking one or two units of alcohol per week or per occasion – produces no ill effects, the study of nearly 12,500 three-year-olds found.
Toddlers born to women who drank lightly during their pregnancy were found to have significantly fewer emotional problems and better cognitive skills than those born to mothers who abstained completely or drunk heavily.
Research into the drinking patterns of the mothers of 12,495 three-year-olds born in Britain found no evidence that drinking lightly at any stage of pregnancy has any discernible effect on the mental development of the foetus and baby. "Our research has found that light drinking does not increase the risk of behavioural difficulties or cognitive deficits [in the baby]," said Dr Yvonne Kelly of University College London, who led the study, published in the International Journal Of Epidemiology.
"Indeed, for some behavioural and cognitive outcomes, those born to light drinkers were less likely to have problems compared to children of abstinent mothers, although those born to heavy drinkers were more likely to have problems compared to children of mothers who drank nothing while pregnant."
The study found that boys born to the mothers who drank lightly were 40 per cent less likely to have "conduct" problems and 30 per cent less likely to suffer from hyperactivity compared to abstinent mothers, even when other factors such as family background and social class were taken into account.
Boys born to mothers who drank lightly also scored higher in tests of vocabulary, or the perception of colour, shapes, letters and numbers compared to boys whose mothers abstained. Girls born to mothers who drank lightly were 30 per cent less likely to have emotional symptoms and peer problems than girls born to abstainers.
It is well established that women who drink lightly are more likely to be better educated and to have a professional career than those who abstain or drink heavily. "People in lower social groups are more likely to abstain from alcohol or drink more heavily than socially-advantaged groups. We can't rule out the effects of social standing on drinking patterns," Dr Kelly said. "However, it may be that light-drinking mothers tend to be more relaxed and this contributes to better behavioural and cognitive outcomes in children."
Government guidelines are for women to abstain from drinking in the first three months of pregnancy due to the risk of miscarriage. Women should take no more than one or two units once or twice a week after that period and avoid binge drinking.