Pregnant women or those trying for a baby should not drink alcohol, the Department of Health said today.
The guidance replaces existing advice which recommends that pregnant women or women trying to conceive should not drink more than one to two units of alcohol once or twice a week, and should avoid getting drunk.
The Department said the new guidance was not based on new scientific evidence but was needed to help ensure that women did not underestimate the risks to their baby.
The guidance comes after a Government survey found that 9% of pregnant women were still drinking above recommended levels.
It says:
:: Pregnant women or women trying to conceive should avoid drinking alcohol.
:: If they do choose to drink, to minimise the risk to the baby, they should not drink more than one to two units of alcohol once or twice a week and should not get drunk.
Deputy Chief Medical Officer Dr Fiona Adshead, said it was to provide stronger, consistent guidance across the UK.
Evidence showed that although all the UK had the same previous guidance, it was being interpreted differently across the countries.
Dr Adshead said: "We have strengthened our advice to women to help ensure that no-one underestimates the risk to the developing foetus of drinking above the recommended safe levels.
"Our advice is simple: avoid alcohol if pregnant or trying to conceive. This advice could also be included on alcohol packaging or labels.
"The advice now reflects the fact the many women give up drinking alcohol completely during pregnancy.
"It is now straightforward and stresses that it is better to avoid drinking alcohol altogether."
The Department of Health said the National Organisation on Foetal Alcohol Syndrome estimates that more than 6,000 children are born in the UK each year with Foetal Alcohol Spectrum Disorder (FASD).
FASD is an umbrella term for a range of problems including physical, mental and behavioural.
For example, a child with FADS may have learning disabilities.
Dr Sheila Shribman, the National Clinical Director for Children, Young People and Maternity Services said: "Alcohol and pregnancy advice is now consistent across the UK.
"Our last survey of pregnant women showed that 9% were still drinking above the recommended levels.
"It is vital that we alert pregnant women and women hoping to conceive about the potential dangers of excessive alcohol consumption during pregnancy.
"Although there is still scientific uncertainty about the precise impact of excess alcohol on unborn babies we believe the time is right to introduce a strong consistent approach across the whole of the UK.
"This revised advice has been agreed by the four chief medical officers across the UK."
Ministers believe the previous advice could suggest it is safe to drink "a little" when pregnant, but the definition of this can vary from person to person.
The Department said women who are already pregnant and who have followed the earlier advice "will not have put themselves or their baby at risk".
Dame Karlene Davis, general secretary of the Royal College of Midwives (RCM), said: "Put simply, women who are trying to conceive or are pregnant should not drink alcohol, and this is the advice that midwives are giving to the women in their care.
"But we know we do not live in an ideal world, and we know that some women may drink alcohol when pregnant, but our advice remains that they should not.
"It is crucial that women are made aware of the potential dangers to their child if they do decide to drink alcohol when pregnant or trying to conceive, and the dangers are there and they are real.
"Midwives have a vital role in informing women about the cumulative effects of alcohol on their unborn child, so that if they make the decision to drink alcohol it is from a position of knowledge about the consequences, not ignorance."
Jane Brewin, chief executive of the baby charity Tommy's, said: "Whether a woman can safely drink alcohol during pregnancy is a contentious issue.
"There is no proven safe level of alcohol to drink during pregnancy because any amount can pass through the placenta to the baby.
"So although one or two units once or twice a week is thought to be safe, Tommy's believes that no alcohol equals no risk.
"Women who drink excessive amounts of alcohol during their pregnancy are taking grave risks.
"These activities can have a severely detrimental effect on the health of their baby.
"Excessive consumption of alcohol or binge drinking can lead to Foetal Alcohol Spectrum Disorder (FASD), which is the leading cause of learning difficulties across the world.
"Alcohol causes more damage to the developing foetus than any other substance, including marijuana, heroin and cocaine."
Source: Press Association, 25/05/2007