How Bad Is Drinking While Pregnant?

It's the first rule of pregnancy-shelve your wine glasses, because you won't be sipping another pinot for at least nine months (cue hormonal tears). However, no drinking while pregnant may not be as strictly enforced as you might think. Between 20 and 80 percent of pregnant women in Ireland drink while they're expecting, while more than 40 percent of women pregnant in the U.K., Australia, and New Zealand imbibe, reports a new study published in BMJ Open. And if those numbers seem crazy to you, consider this: The last similar study in the U.S. published in 2009 estimated that 30 percent of pregnant Americans drank while expecting. (Real women share "Why I Drank During My Pregnancy.")

The subject of drinking while pregnant is a controversial one. There's no doubt that moderate, heavy, or binge drinking can harm a fetus, putting your child at risk for developmental delays, behavioral problems, and physical abnormalities. However, evidence on light drinking is less clear-cut, says Marjorie Greenfield, M.D., a professor of obstetrics and gynecology at Case Western Reserve University and author of The Working Woman's Pregnancy Book.

Some research has suggested that very light drinking-up to one drink a day-might not cause harm. Other research, like a recent study from the U.K., suggests that just drinking that much could lower your child's IQ by up to four points. "Do I recommend having a drink every day in pregnancy?" asks Greenfield. "No, because it's just hard to say it's okay when we know some amount of alcohol causes birth defects." But it does seem insane to say not one drop of alcohol can pass your lips-unless you know you have an alcohol problem and you're not going to be able to stop, she adds.

Greenfield is certain about one thing: You should never, ever become intoxicated while pregnant. But taking a few sips of champagne at a wedding toast probably isn't going to cause big problems. (See: 8 Signs You're Drinking Too Much Alcohol.)

Further complicating matters: It's not clear whether the studies suggesting that light drinking is safe truly say that. "In observational studies, it is true that the results are very conflicting," says Janni Niclasen, Ph.D., an assistant professor of psychology at the University of Copenhagen who studies drinking during pregnancy. The problem stems from the fact that most studies are observational and have no control group. Ideally, to truly find the answer, researchers would have to randomize women to two groups-allowing some to drink and some not to-and study them throughout pregnancy. But, of course, that wouldn't be ethical. (Check out The Body-Altering Effects of Alcohol.)

The safest bet is to abstain, as the Centers for Disease Control and Surgeon General both recommend. "The easiest is to simply recommend no alcohol, because there has been no safe threshold identified," says Aaron B. Caughey, M.D., Ph.D., professor and chair of the department of obstetrics and gynecology at Oregon Health & Science University. He says that more, larger studies would be needed to prove that there's any level of drinking that's okay.

What if you discover that you're pregnant, and you're pretty sure you've had a few cocktails since conception? Don't stress too much. "A small amount of alcohol consumption very early in pregnancy before the pregnancy is even identified is unlikely to cause a problem," says Caughey. In the first four weeks, the embryogenesis-or time before the embryo becomes a fetus-hasn't occurred yet so light alcohol doesn't have much to damage.