Women worried by guidance advising abstinence should be told there is little evidence that the odd glass of wine causes harm to the baby, says study

Mothers who are consumed by anxiety and guilt for having drunk the odd glass of wine when they are pregnant should be reassured by a new study showing there is very little evidence that it harms the baby, say experts.

Drinking in pregnancy is a fraught issue and causes much anxiety. Last year new guidance to the NHS in England urged women to try not to drink at all, but in the real world, say the new study’s authors, up to 80% in the UK, Ireland, New Zealand and Australia drink some alcohol while they are pregnant. Since half of all pregnancies are unplanned, many women drink before the test shows positive.

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Although there is strong evidence that excessive drinking harms babies in the womb, the study from researchers at the University of Bristol found that few good studies had been done on light drinking, which they defined as no more than two small drinks, or four units per week.

“Despite the distinction between light drinking and abstinence being the point of most tension and confusion for health professionals and pregnant women and contributing to inconsistent guidance and advice now and in the past, our extensive review shows that this specific question is not being researched thoroughly enough, if at all,” they write in the BMJ Open journal.

Without the evidence, it is impossible to say whether drinking small amounts is safe or not, they say. “Formulating guidance on the basis of the current evidence is challenging,” they say. They agree that drinking no alcohol in pregnancy is the safest option, but women should be told that little research has been done on light drinking, although they should also be informed that “absence of evidence is not evidence of absence,” they write.

A number of experts said women who had been alarmed by the NHS abstinence guidance would be relieved. “This valuable and humane study has shown that warnings about the dangers of drinking any alcohol at all during pregnancy are not justified by evidence,” said David Spiegelhalter, Winton professor for the public understanding of risk at the University of Cambridge.

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“A precautionary approach is still reasonable, but with luck this should dispel any guilt and anxiety felt by women who have an occasional glass of wine while they are pregnant.”



Dr Christoph Lees, clinical reader in obstetrics at Imperial College London, said the study showed the weakness of the evidence behind the official guidance. “Whilst it is possible that light drinking is associated with a slightly higher risk of having a small baby, there are other possible explanations. It will be an important challenge for those responsible for public health messages to convey nuanced advice that explains how robust or otherwise the evidence is,” he said.

Professor Russell Viner from the Royal College of Paediatrics and Child Health took a different perspective on the same study, however. “This research confirms that based on current evidence it is impossible to say what constitutes a ‘safe’ amount of alcohol a woman can drink if she’s trying for a baby and for women who are pregnant.

“My advice to women is that it’s best not to drink at all if you’re trying for a baby or pregnant. Regularly drinking even small amounts could be harmful and should be avoided, in line with the precautionary approach.”

Justine Roberts, founder and CEO of Mumsnet, welcomed the study: “Unlike the no-smoking message, which seems to be universally believed if not always adhered to, pregnant women have remained a little sceptical about the zero-alcohol advice, and judging from the Mumsnet forums tend to be pretty realistic about the probable impacts of the odd drink and see no point in dwelling on the amounts they drank before even knowing they were pregnant.”