Alcohol use during pregnancy is "prevalent and socially pervasive" in the UK and Ireland, health experts have warned after carrying out a large scale study.
Women across all socio-demographic groups were likely to drink - but those who smoked were up to 50% more likely to consume alcohol while pregnant, research led by the University of Cambridge found.
Researchers described the widespread consumption of even low levels of alcohol during pregnancy as a "significant public health concern".
Their analysis of almost 18,000 women in the UK, Ireland, New Zealand and Australia found drinking during pregnancy was commonplace in all four countries, ranging from 20% to 80% in Ireland and from 40% upwards in the UK, Australia and New Zealand.
Ireland had the highest prevalence of any alcohol consumption pre-pregnancy (90%) and during pregnancy (82%), and the highest reported binge consumption before (59%) and during (45%) pregnancy.
The amount of alcohol consumed dropped substantially for all countries in the second trimester, along with the level of binge drinking.
Non-white women were less likely to drink, along with younger women, those who were more highly educated, obese or already had children.
Researchers said the findings show there is low adherence to alcohol guidelines advising complete abstinence from alcohol during pregnancy in Ireland, New Zealand and Australia, and the National Institute for Health and Care Excellence (Nice) guidelines in the UK advising consumption of no more than one to two units once or twice a week.
Although most women who drink during pregnancy do so at low levels, those who drink heavily are putting their unborn baby at risk of Foetal Alcohol Syndrome (FAS), which affects their physical and mental development.
The team added that since most women who consume alcohol do so at lower levels, where the effects on the foetus are less well understood, the "widespread consumption of even low levels of alcohol during pregnancy is a significant public health concern".
Their analysis did not include women who miscarried or who had stillborn babies - and they said this meant they could have excluded the heaviest drinkers of all, and participants may also be more advantaged than the general population, which could have affected the results.
"The findings of this study have direct application to policy and practice," the study authors concluded.
"Although low proportions of women engaged in heavy drinking, the adverse consequences of heavy alcohol consumption during pregnancy on birth outcomes, long-term gross motor function, and social, cognitive, emotional and behavioural outcomes in offspring make heavy gestational alcohol consumption a high public health priority.
"Additionally, since most women who consume alcohol do so at lower levels where the offspring growth and development effects are less well understood, the widespread consumption of even low levels of alcohol during pregnancy is a significant public health concern."
They added that healthcare professionals should advise pregnant women to abstain from alcohol during pregnancy, while dual targeting of smoking and alcohol consumption should potentially be increased.
"New policy and interventions are also required to reduce alcohol prevalence both prior to and during pregnancy," they added.
Last month, former Children's Commissioner for England Professor Sir Al Aynsley-Green spoke out against the ''political denial'' and ''inconsistent and contradictory advice'' that he said comes from health agencies on whether women should drink alcohol when pregnant.
Prof Aynsley-Green said there are currently ''seriously limited services to support'' infants born with FAS, telling delegates at the British Medical Association's (BMA) annual representatives' meeting in Liverpool that up to 6,000 babies are born every year with the condition.
"In England, the RCM (Royal College of Midwives) says don't drink, otherwise there is political denial," he said.
"There is inconsistent and contradictory advice from the DH (Department of Health) and from Nice. And there are seriously limited services to support affected infants.
''We believe it's time for concerted, political action and leadership, from Government, the alcohol industry, medical professionals and supporting agencies to work alongside women, families and affected adults and children.''
Clare Murphy, director of external affairs at the British Pregnancy Advisory Service (Bpas), said: "Although the authors describe these findings as raising significant public health concerns, the majority of women in the UK are drinking well within the existing recommendations in the second trimester.
"The prevalence of unplanned pregnancy in this country means many women may have an episode of binge drinking before they realise they are pregnant, but the monumental drop in reported binges by the second trimester suggests women alter their behaviour very quickly.
"Bpas regularly sees women so concerned about the damage caused by an episode of binge drinking before they recognised they were pregnant they consider ending what would otherwise be a wanted pregnancy. We would like to see greater reassurance to these women that they are extremely unlikely to have caused their baby harm."
Louise Silverton, director for midwifery at the Royal College of Midwives (RCM), said: "The overall number of pregnant women who continue to drink alcohol during pregnancy is very concerning, as there is no evidence that any level of consumption is safe for the growing baby.
"This is why the RCM continues to advise women to abstain from drinking alcohol when pregnant or if trying to conceive. Drinking around conception and during the first three months may also increase the chance of having a miscarriage."