Drinking one or two units of alcohol a week during pregnancy does not harm a child's development, experts have said.
Women can safely drink a 175ml glass of wine, a 50ml glass of spirits or just under a pint of beer each week without affecting intellectual or behavioural development, according to a new study.
But children born to mothers who drink heavily or binge drink (seven or more units a week or six at one sitting) are at higher risk of behavioural and emotional problems.
The finding adds to previous research which found light drinking has no negative effect on toddler development.
For the latest study, experts examined the risk of drinking on children up to the age of five.
The issue of how much is safe to drink during pregnancy has caused controversy in recent years.
In 2007, the Department of Health published guidance saying pregnant women should avoid drinking alcohol altogether, as should those trying to conceive.
This replaced previous guidance which said it was safe for pregnant women to drink one to two units of alcohol per week.
The Government said its update was not based on new research, but was to provide consistent advice to all women.
Heavy drinking in pregnancy is linked to the Foetal Alcohol Spectrum Disorder (FASD) in children, which can cause a range of physical, mental and behavioural problems.