Women who have one or two alcoholic drinks a week during pregnancy do not harm their children's behavioral or intellectual development, according to a study by British scientists on Wednesday.
The researchers found that pregnant women who drank up to a glass of wine, up to 50 ml of spirits or just under a pint of beer a week did not affect their children.
But children whose mothers were heavy drinkers were more likely to be hyperactive and have behavioral and emotional problems than those whose mothers did not drink during pregnancy, the scientists said.
Yvonne Kelly of the epidemiology and public health department at University College London said the findings helped fill a gap in scientific research about the risks of alcohol and pregnancy, which has mostly focused on risks of heavy drinking.
"We're talking about one or two drinks a week at the very most," Kelly said in a telephone interview. "Light drinkers would also include women who have a very occasional drink at a family celebration for example."
Previous studies have shown that heavy alcohol drinking during pregnancy can seriously harm the baby and many health authorities advise women to keep alcohol intake to a minimum when they are pregnant.
In their study, Kelly's team used data from the Millennium Cohort Study - a large study tracking the long-term health of children born in the UK - taking a representative sample of 11,513 children born between September 2000 and January 2002.
The mothers were questioned about their drinking habits during pregnancy and their children's behavior at the age of three, and the children's behavioral and intellectual progress was then formally assessed at the age of five.
The women were classified either as teetotal, those who drank but not in pregnancy, light drinkers (up to one or two drinks a week), moderate drinkers (three to six drinks a week); and binge or heavy drinkers (seven or more drinks a week, or six at any one time).
The results, published in the Journal of Epidemiology and Community Health, found no evidence to suggest that the behavioral or intellectual development of children born to light drinkers was compromised.
"Up to the age of five years there is no increased risk of poor socio-emotional or cognitive developmental outcomes in children born to mothers who drank not more than one or two units of alcohol per week during pregnancy," the scientists wrote.
Across the entire range of children of non-drinkers and drinkers, the study found that boys were more likely than girls to have more developmental problems and also more likely to have behavioral issues, be hyperactive, and have problems with peers. Girls were more likely to have emotional problems.