Is binge drinking in pregnancy safe?

By Rachel Liddle, rachel.liddle@haymarket.com on the 21 November 2007

Reports say that binge drinking might not cause foetal damage.

What is the story?
Occasional binge drinking in pregnancy might not damage the foetus, according to media reports.

Heavy drinking throughout pregnancy is linked to birth defects, but there is little evidence that the odd binge drinking session has the same effect if overall alcohol intake during pregnancy is low, say the papers.

A binge drinking session is the equivalent of having five or more drinks in one sitting.

The latest research goes against DoH advice for pregnant women to limit alcohol intake to one or two drinks a week. It also contradicts the BMA view that pregnant women should avoid alcohol altogether, say the papers.

What is the research?
The findings come from a systematic review of the effects of binge drinking in pregnancy.

The University of Oxford team carried out the study because although the dangers of heavy drinking in pregnancy are known, there is little consensus on the effects of occasional binge drinking in women who, overall, have low to moderate alcohol intake.

A literature search of English-language papers published between 1970 and 2005 yielded 3,630 papers. Closer examination reduced these to 14 relevant studies carried out in the US, UK, Australia, Denmark and Canada.

There were considerable differences in what was considered a 'binge' between studies. Most commonly it was five or more drinks on a single occasion - equivalent to 7.5 UK units.

Among the seven studies which considered outcomes related to birth weight, gestation and growth, the researchers found it difficult to separate the problems of heavy and binge drinking.

When the team focused on foetal alcohol syndrome, which featured in three of the studies, a slight excess in birth defects was noted among bingers.

However, the findings were clouded by non-adjustment for confounding factors or a lack of statistical significance.

When the researchers looked at the impact of binge drinking on neurodevelopment outcomes, some evidence of a positive association was found.

One study found children of women who binged in pregnancy were more likely to have 'disinhibited behaviours' than those born to mothers who did not.

A second study found a significant reduction in verbal IQ and an increase in delinquent behaviour if mothers binged in pregnancy.

But two other studies found no statistically significant differences in development at 18 or 36 months between children of women who binged and those who did not.

What do the researchers say?
Lead researcher Dr Ron Gray, a clinical epidemiologist at the University of Oxford, stressed that his team were not advocating binge drinking in pregnancy.

'We looked at how binge drinking might be harmful during pregnancy and we found there was some suggestion that it might be harmful to the neurodevelopment of the child, but not much evidence that it would cause other harms,' he said.

'We don't think that binge drinking isn't harmful but that these studies don't show it.'

However, Dr Gray said: 'Some women will go to their doctor and report isolated episodes of binge drinking. We think at this time it's unnecessary to make these women anxious.'

Nevertheless, until more research is carried out, pregnant women should continue to follow DoH advice, he stressed.

What do other experts say?
The UK's four CMOs say women should avoid alcohol if trying to conceive and when pregnant. Those who do drink should limit this to one or two units a week.

A DoH spokeswoman said this would not change. 'There is only a limited evidence base in this area and we think it is best to err on the side of caution.'

A BMA spokesman said: 'What we do know is that women want the best for their unborn child and the BMA would advise women to abstain.'

WHAT THE PAPERS SAID