Pregnant women are being advised not to drink any alcohol during the first three months of pregnancy by a health watchdog that last year said would-be mothers could drink a glass of wine every day.

The National Institute for Health and Clinical Excellence (NICE) will also say that from the fourth month of pregnancy onwards women should never drink more than a small amount on only one or two days a week. The volte-face by the watchdog brings its advice more into line with the Department of Health’s abstinence message, which said in May last year that pregnant women should cut out drinking altogether.

The new guidelines were welcomed by Professor Sir Liam Donaldson, the Government’s Chief Medical Officer, who said it highlighted that there were increased risks of miscarriage at the beginning of pregnancy.

He added: “It again reinforces that if they do choose to drink, to protect the baby they should not drink more than one to two units of alcohol once or twice a week and should not get drunk.”

The final version of the guidelines will also say that woman who are planning to get pregnant should stop drinking entirely.

However, NICE’s draft guidance, issued last autumn, said that there was no evidence that a small glass of wine every day caused any harm after the first trimester. It said at the time that there was no “consistent evidence” to show that a small amount of alcohol damaged unborn children.

Rhona Hughes, a consultant obstetrician who chaired the group developing the guidelines, said that changes in the final version were not based on fresh scientific evidence, adding that the quality of data on the effects of alcohol in pregnancy was poor. She said: “There’s no evidence of definite harm of drinking that level of alcohol per week \, but we are unable to guarantee women that there will be no harm.”