Controversy continues over drinking in pregnancy

The controversy regarding what advice women should be given about drinking low to moderate amounts of alcohol during pregnancy has again been highlighted in the newspapers. A headline in The Daily Telegraph today read “Pregnant women told to keep off alcohol”, and goes on to say that women “should abstain from drinking alcohol or risk damaging the health of their child”. The Daily Express headline stated that “Drinking is a mum's choice”; the newspaper said that “women should be left to decide if they want to drink small amounts of alcohol during pregnancy”.

These stories are based on two opinion pieces from experts, which present two opposing views about whether women should be advised that drinking small amounts of alcohol during pregnancy was safe. It should be emphasised that both sides agree that drinking large amounts of alcohol during pregnancy has serious detrimental effects on the health of the baby.

Where did the story come from?

The opinion pieces were written by Dr Pat O’Brien, an obstetric consultant from University College London Hospitals, and Prof Vivienne Nathanson and two colleagues who work for the British Medical Association in the areas of science and health policy. Both opinion pieces were published in the British Medical Journal .

What kind of scientific study was this?

The two papers were part of a “Head-to-Head” feature, where two experts in the field with opposing views put forward their opinions about a topical issue; in this case, whether it is all right for women to drink even small amounts of alcohol during pregnancy. Both sets of experts discussed their professional opinions and experience, and supported these by referencing the medical literature.

What were the results of the study?

Dr O’Brien notes that until recently, the Department of Health advised that drinking small amounts of alcohol (no more than one to two units of alcohol once or twice a week) was permissible, but that this position has now been changed to suggest that women should not drink alcohol at all while pregnant. He argues that there has been no change in the scientific evidence during this time and that there is no reason to alter the recommendation. To support his view, he discusses a review by the Royal College of Obstetricians and Gynaecologists published in 2006, which concluded that there was no evidence that consuming a small amount of alcohol in pregnancy is harmful. He also includes similar statements from the National Perinatal Epidemiology Unit in 2006, the Medical Council on Alcohol, the Midwife Information and Resource service in 2003, and the National Institute for Health and Clinical Excellence. He argues that we should allow pregnant women to make their own decision, supported by improved communication by medical professionals of what the current evidence suggests are safe limits.

Prof Nathanson and colleagues state that a new BMA report supports the most recent UK government advice that pregnant women and women trying to conceive should abstain from alcohol. They mention other bodies and professionals which support this advice , including the World Health Organisation, the governments of America, Canada, France, New Zealand, and Australia, the UK’s Royal College of Obstetricians and Gynaecologists, and the US surgeon general. They acknowledge the controversy surrounding low to moderate alcohol consumption during pregnancy, and suggest that this may be due to problems with how the research in this area has been conducted and analysed, the differences in how alcohol consumption is measured and categorised, and in how we assess what factors, such as a person’s genetic makeup, affect the outcome. They suggest that there is emerging evidence that low to moderate alcohol consumption may be harmful, including results from animal studies, studies showing effects of alcohol on foetal breathing, and that children’s behaviour and mental health may be negatively affected by low to moderate alcohol consumption during pregnancy.

What interpretations did the researchers draw from these results?

Dr O’Brien concludes that women should be allowed to decide whether or not to consume small to moderate amounts of alcohol during pregnancy.

Prof Nathanson and colleagues conclude that in light of uncertainty about the effects of low to moderate alcohol consumption in pregnancy on the foetus, the absence of clear guidelines, and people’s confusion about how to measure alcohol intake, the best advice is that women who are pregnant or planning to become pregnant should abstain from alcohol completely.

What does the NHS Knowledge Service make of this study?

The issue of alcohol consumption in pregnancy is an important and emotive issue. Both of these pieces are based on the opinions of the authors, based on their interpretation of the available scientific evidence, and on the opinions of various professional and governmental bodies. Both sides agree that heavy alcohol consumption during pregnancy is detrimental to the baby and should be avoided. They also both highlight the fact that there is often confusion about what constitutes a “unit” of alcohol, which can make it difficult for people to know how much alcohol they are consuming.

Sir Muir Gray adds...

The fact that there is no evidence does not mean that there is no effect, only that the research that has been done so far shows no association at low levels of alcohol consumption.

It is very unlikely that there is a lower threshold below which there is no risk of harm; the distribution of risks is usually continuous, that is if a risk can be demonstrated at high level of exposure there is almost always a risk at all levels of exposure but the demonstration of that risk is difficult.