National Institute for Health and Care Excellence urges women to avoid alcohol in the first three months of pregnancy in particular." width="1000" height="600" class="gu-image" />

“Thousands of middle class mums-to-be putting babies at risk with light drinking” is the headline on one news website, as the complex issue of drinking during pregnancy rears its head once more.

In a field where consensus is conspicuously lacking, the latest headlines are based on a discussion in the BMJ in which two experts argue that complete abstinence is the “only ethical advice that can be given”.

The government’s chief medical officer recommends that pregnant women should avoid alcohol. But it comes with an important rider, namely that “if you do opt to have a drink, you should stick to no more than one or two units of alcohol (equivalent to one or two small glasses of wine) once or twice a week to minimise the risk to your baby”.

Further – or conflicting, according to your point of view – advice from the National Institute for Health and Care Excellence (Nice) urges women to avoid alcohol in the first three months in particular, because of the increased risk of miscarriage; this guidance is supported by the Royal College of Obstetricians and Gynaecologists.

In the BMJ, Mary Mather, a retired paediatrician, and Kate Wiles, a doctoral research fellow in obstetric medicine at Guys and St Thomas NHS trust, argue that the guidance is inconsistent and that many countries advise against alcohol consumption completely. However, the counter argument is that many countries do not; and in at least two of the countries that do – Australia and Ireland – drinking while pregnant is said to be common (as it is in the UK).

Mather and Wiles argue that infants can suffer from foetal alcohol syndrome, mental retardation, development and behavioural abnormalities, and low birth weight.

They say that “there is no evidence of a threshold level of alcohol consumption in pregnancy below which there can be certainty that exposure is safe” (binge-drinking is well-established to pose serious risks).

Even the expert on the other side of the BMJ discussion – Patrick O’Brien, a consultant and honorary senior lecturer in obstetrics and gynaecology at University College London hospital – agrees that there can never be a 100% guarantee that any lower limit is safe. But equally, O’Brien says there is no robust evidence that drinking within advised limits after 12 weeks of pregnancy is harmful for the foetus.

A major 2010 study by University College London’s department of epidemiology and public health investigated the drinking behaviour while pregnant of the mothers of 11,500 babies, and looked at the health of the children by the age of five. The results provided some comfort to women who drink moderately during pregnancy.

The children of heavy drinkers were more likely to be hyperactive and have behavioural and emotional problems, but the babies who were born to light drinkers suffered no ill effects.

But as O’Brien says, the evidence is not certain. He therefore advises that women should be told what the evidence is and its limitations so that they can make an informed decision. He too bemoans “a raft of conflicting guidance for women”.

Whether it is the conflicting guidance and headlines or a lack of advice from medical professionals, most mothers are unaware of the official limits, according to a YouGov poll for the charity Drinkaware. It found half of those surveyed were not given any advice about drinking while pregnant and only a fifth knew what the current guidance was. But reassuringly for those who urge abstinence, the remaining four-fifths thought the guidance stricter than it actually is.