One in 100 babies are born in Britain each year brain-damaged with Foetal Alcohol Spectrum Disorder (FASD), caused by women consuming alcohol while pregnant.
Health officials say exposure to alcohol before birth is the "single most important preventable cause of incurable brain damage".
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The Government's current advice to women who are pregnant is to avoid alcohol.
However, guidelines also state: "If women do choose to drink, to minimise the risk to the baby, we recommend they should not drink more than one to two units once or twice a week and they should not get drunk."
The guidance has been branded inconsistent, with critics arguing that pregnant women need to be told to avoid alcohol altogether - advice which is already issued in countries such as the US, Canada, Australia and France.
One expert points to evidence suggesting that even when drinking just one unit of alcohol - within the government guidelines - the foetus stops moving and breathing for up to two hours.
Consultant Paediatrician Dr Mary Mather said American researchers had found evidence that alcohol can have a worse impact on foetuses than heroin, cocaine, cannabis and tobacco.
Children diagnosed with FASD will experience a range of developmental, social and learning difficulties throughout life.
While some FASD sufferers have distinct facial features, such as small and narrow eyes and a small head, many will not have any facial deformities - leaving them with an invisible disability which may not be diagnosed.
Experts say children may not show signs of FASD until they start school and display problems interacting with others.
Other symptoms can include:
Lack of social boundaries such as over-friendliness
Inability to listen to instructions
Difficulty with group interaction
Sam, who admits to binge drinking consistently during her pregnancy, resulting in her son, Stanley, suffering frontal lobe brain damage, told Exposure she was not given any advice by doctors or midwives about alcohol.
"Had I known the facts it might have shocked me enough to try and seek further help."
She added: "He [Stanley] knows that he's got brain damage because of it. He does express his anger sometimes and it's, 'you have made me like this', which is you know horrible."
Professor Sir Al Aynsley-Green, the former First Children's Commissioner for England, said the current guidelines leave women "confused and anxious" and unable to make important decisions when pregnant.
“Exposure to alcohol before birth is the single most important preventable cause of incurable brain damage,” he said.
Sir Al recalled how Canadian health officials told him that Britain was "sleepwalking" over the issue.
"When I was in Canada describing to them the lack of focus and effort in this country, they said to me 'why are you guys sleepwalking over the single most important preventable cause of incurable brain damage in children today?'"
Dr Raja Mukherjee, lead clinician at the only NHS clinic specialising in FASD, said alcohol affects brain development in the foetus at every stage of a pregnancy.
"What's it's doing is it's stopping normal development, it's interfering with the process, so you’ve got brain cells being killed off, you get brain cells in the wrong place, you’ve got parts of the brain that just are absent,” Dr Mukherjee said.
Dr Mather said women need to be informed that there is no safe drinking limit during pregnancy.
“Alcohol is a poison, it’s a toxin, it’s toxic to developing tissue and it’s also what doctors call a Teratogen. And the best known Teratogen is obviously Thalidomide,” Dr Mather said.
"I think British women are actually deprived of information, I really do.
"I think that treat British women like children really, we don’t give them the information that they need to make the decisions they've got to make.
"They probably should be panicked. This is an incurable lifelong disability. I think it’s time the professionals started to give pregnant women clear advice about the real risks in pregnancy."
Jane Ellison, the Minister responsible for the Government's policy on alcohol, declined to be interviewed as part of Exposure's investigation.
Instead, the Department for Health set out its current advice and said the Chief Medical Officer is currently reviewing the guidelines.
Watch Exposure: When Pregnant Women Drink on ITV at 9pm on March 3