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A new study out of the U.K. weighs in on a question many parents who are expecting a baby wonder about. Is it risky to drink a little alcohol during pregnancy? NPR's Allison Aubrey reports it turns out to be a tricky question to answer.
ALLISON AUBREY, BYLINE: In some countries, it's not uncommon for women to drink while pregnant. A recent study found 20 to 80 percent of women surveyed in the U.K., Ireland, New Zealand and Australia consumed some amount of alcohol during pregnancy. And researcher Luisa Zuccolo of the University of Bristol says she and her colleagues wanted to know if there was evidence to show that light drinking was risky.
LUISA ZUCCOLO: So this is exactly the question that we were trying to answer. And we were comparing drinking once or twice a week compared to not drinking at all.
AUBREY: They pulled together data from prior research and found that compared to women who abstained, women who consumed alcohol had small increased risks - for instance, lower birth weight.
ZUCCOLO: What we found was that there was an 8 percent increased chance of having babies smaller than expected at birth for women that drank up to about 32 grams of alcohol a week.
AUBREY: That's between two to three drinks per week. But Zuccolo says it's not clear if the increased risk was caused by the alcohol or by other factors like smoking. She says it's tricky for scientists to study this.
ZUCCOLO: Now, obviously you can't do a randomized control trial and ask some women to drink and some women not to drink because that's not ethical.
AUBREY: Not ethical because you don't know if you're putting their babies at risk. Scientists don't know if there's any safe threshold for alcohol during pregnancy. Here's maternal-fetal medicine specialist David Garry of Stony Brook University Hospital.
DAVID GARRY: We don't 100 percent understand exactly when and how and what point in pregnancy that the effects occur from alcohol.
AUBREY: He says given this, the best advice is to avoid alcohol completely during pregnancy. He says risks of heavy drinking are well-documented. Fetal alcohol spectrum disorder can lead to birth defects and a range of serious problems. So he says, why risk it?
GARRY: By simply not drinking, you can prevent the problem. Other words - not drinking and pregnancy equals no fetal alcohol spectrum disorders, and that's very clear.
AUBREY: This precautionary principle is the basis of guidelines around the globe that advise pregnant women to abstain, even in countries where wine is woven into the culture such as France. But Luisa Zuccarello, who's Italian, says cultural norms can be slow to change.
ZUCCOLO: Italy's is a country who loves their wine. And when I was growing up, the culture around the drinking and pregnancy was much more relaxed than it is now.
AUBREY: Recently Italy updated its guidance recommending complete abstention from alcohol when pregnant. Allison Aubrey, NPR News.
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