Despite the familiar surgeon general's warning advising women to abstain completely from alcoholic beverages during pregnancy "because of the risk of birth defects," there has never been any solid evidence that light to moderate consumption harms the fetus (as Stanton Peele pointed out in Reason more than two decades ago). New research from Denmark, funded by the U.S. Centers for Disease Control and Prevention, indicates once again that heavy drinking is the real hazard. In a study of more than 1,600 women ("nearly a third of all Danish women who were pregnant between 1997 and 2003," Maia Szalavitz notes in Time), children of women who consumed nine or more drinks per week during pregnancy had shorter attention spans and were five times as likely to have low IQs at age 5 than children of abstainers. But no such effects were apparent in the children of women whose alcohol consumption during pregnancy was light (one to four drinks per week) or moderate (five to eight drinks per week). "Our findings show that low to moderate drinking is not associated with adverse effects on the children aged 5," the researchers said.

Szalavitz cautions that a "drink" as defined in this study contained 12 grams of pure ethanol, compared to the American standard of 14 grams, one-sixth more. Given the relatively wide consumption ranges, that difference probably does not matter much. Szalavitz also notes that, unlike earlier studies, this one asked women about their drinking while they were still pregnant, so the responses are less likely to be skewed by inaccurate recall. Still, self-reported drinking, especially by pregnant women, probably underestimates actual consumption, meaning that the amounts associated with no neurological impairment are apt to be bigger than those indicated by the study.

Bruce Goldman, director of substance abuse services at the Zucker Hillside Hospital in Glen Oaks, New York, considers the new research unhelpful. "These findings can easily send a very dangerous message to pregnant women," he tells CBS News. "Women may underestimate and have difficulty acknowledging the frequency or quantity of alcohol consumed. Those suffering from alcoholism may attempt to rationalize that it is safe to drink moderately, something they may ultimately be unable to do." 

Likewise, the CDC is not changing its recommendation of complete abstinence in light of the new data, since it is still true (and always will be, given the possibility of subtle effects beyond the ability of scientists to measure) that no safe level of alcohol consumption during pregnancy has been conclusively established. Life (and preganancy) is full of risks, however, and this one seems small enough that reasonably prudent people may be willing to accept it. At the very least, women should not feel guilty about the occasional drink during pregnancy, and people should not glare at an expectant mother who orders a glass of wine as if she were leaving her infant in the car on a hot day.

Previous coverage of drinking during pregnancy here.

[Thanks to Baked Penguin for the tip.]