Alcohol, pregnancy and the precautionary principle
A recent study showed no evidence of an adverse effect of moderate consumption of alcohol during pregnancy and subsequent child development. But the Department of Health has commented "After assessing the available evidence, we cannot say with confidence that drinking during pregnancy is safe and will not harm your baby. Therefore, as a precautionary measure, our advice to pregnant women and women trying to conceive is to avoid alcohol."
Is this still a tenable position?
The precautionary principle is intended to cover situations where there is a possibility of harm but little evidence exists, and so to be on the safe side a recommendation is made to avoid exposure to the possible hazard. It is based on the popular idea that ‘no evidence of harm’ is not the same as ‘evidence of no harm’. But this old adage does not hold when there has been substantial research done and no indication of harm found.
The Department of Health is reporting as saying that that it wants to offer consistent advice that will not confuse people. We know that the constantly changing stories in the media about is safe and what is not safe can lead to bafflement. But the attitude of the Department could also be interpreted as being patronising and arrogant, and takes no account of the possible cost, in terms of reputation and trust, of providing advice that contradicts the available evidence. Let alone the increased anxiety and guilt of women who have a drink while they're pregnant.
Pregnant women should limit their alcohol intake to less than one standard drink (1.5 UK units or 12g of alcohol) per day and if possible avoid alcohol in the first 3 months of pregnancy.
Women should be informed that binge drinking (defined as more than 5 standard drinks on a single occasion) may be particularly harmful during pregnancy.
(NICE 2007 p.36)
In spite of this pressure, NICE only slightly changed its view, and the final version of the guidelines which appeared in March 2008 (pdf) say:
If you are pregnant or planning to become pregnant, you should try to
avoid alcohol completely in the first 3 months of pregnancy because
there may be an increased risk of miscarriage.
If you choose to drink while you are pregnant, you should drink
no more than 1 or 2 UK units of alcohol once or twice a week.
There is uncertainty about how much alcohol is safe to drink in
pregnancy, but at this low level there is no evidence of any harm to
the unborn baby.
You should not get drunk or binge drink (drinking more than 7.5 UK
units of alcohol on a single occasion) while you are pregnant because
this can harm your unborn baby.
It is reassuring to see NICE showing its independence from the Department.
In fact, as covered by Straight Statistics, the study even points to a possible protective effect of alcohol. This is likely to be a statistical artefact, but even considering this possibility is clearly as unthinkable as in the Million Women study, where teetotallers were simply eliminated from the analysis in spite of them displaying higher cancer rates than moderate drinkers.