Women have been advised that official guidance to avoid alcohol in pregnancy remained in place after experts said drinking one or two units a week does not harm a child’s development.
Mothers-to-be 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.
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.
Following the latest study, in which experts examined the risk of drinking on children up to the age of five, a spokeswoman for the Department of Health said: “After assessing the available evidence, we cannot say with confidence that drinking during pregnancy is safe and will not harm your baby.
“Therefore, as a precautionary measure, our advice to pregnant women and women trying to conceive is to avoid alcohol.”
Janet Fyle, professional policy adviser at the Royal College of Midwives, said she was concerned women may take the findings as a message that it is “OK” to drink alcohol.
“There is no firm evidence that small amounts of cumulative alcohol consumption does not have an effect on the developing foetus,” she said.
“Because of this our advice to women remains the same; if you are planning to become pregnant, or if you are pregnant, it is best to avoid drinking alcohol.”
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.
In the latest study, led by a team at University College London, experts questioned mothers from more than 11,000 households.
In the first phase, when babies were nine months old, mothers were asked about their drinking in pregnancy alongside other health aspects, such as smoking, their socio-economic status and other factors that may influence the results.
Visits were also made when the children were aged three and five years.
Assessment of development, social and emotional behaviour at the age of five showed that boys and girls born to mothers who had one or two units of alcohol per week scored slightly higher on some tests than those born to mothers who had not touched alcohol in pregnancy.
Dr Yvonne Kelly, from University College London, who led the study published in the Journal of Epidemiology and Community Health, said: “Our message is that there’s no increased risk of difficulties in children born to mothers who drink one to two units a week.”
She said the sample of light drinkers was varied, and included some women who consumed one or two units every week and women who enjoyed the odd glass.
“This might include women who’ve had the odd glass of wine at an important family celebration,” she said.
“It’s certainly not that all of these women were having one or two glasses every week.”
Dr Tony Falconer, president of the Royal College of Obstetricians and Gynaecologists, said: “Government guidance on alcohol consumption during pregnancy states clearly that the safest choice is abstinence.
“However, if a woman would like to have a drink, the current evidence shows that drinking one or two units, once or twice a week is acceptable.
“If a pregnant woman is unsure about how much she is drinking, she should discuss the matter with her midwife or GP.
“Anecdotally, the majority of women are responsible and tend to stop drinking once they find out they are pregnant.
“But with rising levels of binge drinking among younger women, we are concerned about those who find it difficult to wean themselves off alcohol as heavy, sustained drinking will damage the foetus.”
Chris Sorek, chief executive of the charity Drinkaware, said: “Despite these findings, it is important to remember that ‘light drinking’ can mean different things to different people.
“There is a risk that if pregnant women take this research as a green light to drink a small amount, they could become complacent, drink more than they think they are and inadvertently cause harm to their unborn child.”