When it comes to drinking alcohol during pregnancy, some women wonder: Is it OK to have one drink?
"I do get that question often," says David Garry, a maternal-fetal medicine specialist at Stony Brook University Hospital. And, he says his answer is clear.
"There is no safe level of alcohol use during pregnancy," Garry explains, citing guidance from the American Congress of Obstetricians & Gynecologists.
The majority of women in the U.S. seem to be on board with this message. According to the CDC, about 90 percent of pregnant women say they refrain, though some may drink without disclosing it. "There's a social stigma to drinking in pregnancy, which is a good thing," Garry says.
In other countries, however, alcohol use during pregnancy appears to be more common. A 2015 study found that alcohol consumption ranged from 20 percent to 80 percent among cohorts of women in Australia, New Zealand, Ireland and the United Kingdom. The study found that some pregnant women may have had just one drink — say, a glass of bubbly at a special event such as a wedding; others reported consuming a drink or two more regularly.
So, how risky is this? A new analysis, published this week in BMJ Open, aimed to answer this question. Researchers collected all the available data they could find from prior studies that had assessed the risks of drinking while pregnant.
"We compared drinking once or twice a week [at low levels] compared to not drinking at all," explains study author Luisa Zuccolo, a health epidemiologist at the University of Bristol.
Zuccolo and her co-authors found that consuming up to 32 grams of alcohol a week ( which is between two and three drinks) was associated with a 10 percent increased risk of preterm birth. However, it's not clear if this increased risk is caused by the alcohol exposure, or by other factors.
Overall, Zuccolo says, "we were surprised by how few studies have been published ... on such an important topic."
She says that, given the lack of robust data, it's hard to answer the question: Is one drink during pregnancy safe? And she and her co-authors conclude that further studies are needed to provide "a better estimation of the likely effects."
But experts say the lack of evidence is not a reason to challenge the current advice to avoid alcohol entirely during pregnancy.
"We don't 100 percent understand exactly when and how — and at what point in pregnancy — the effects occur from alcohol [consumption]," says David Garry, who is also a spokesperson for the American Congress of Obstetricians & Gynecologists.
But he says, think of it this way. The harms of alcohol consumption during pregnancy, especially heavy drinking, can be far-reaching. Fetal alcohol spectrum disorder can lead to everything from birth defects to intellectual development problems to struggles with mental health. "It's everything from mild to severe problems."
"By simply not drinking, you can prevent the problem," says Garry. So, why take a risk?
This precautionary principle has become the basis of guidelines around the globe. Even countries where wine is woven into the culture, such as France, advise women that it is safest not to drink alcohol at all during pregnancy.
And, recently, Italy updated its guidance as well. This informational leaflet for Italian women says "50-60 percent of pregnant women in Italy consume some alcoholic beverages." Then, it warns: "Even minimal amounts of alcohol [during pregnancy] could harm the baby's health and development."
KELLY MCEVERS, HOST:
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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