June 22, 2012 -- A drink or two each week during pregnancy may not affect a child's general intelligence at age 5, according to a new series of Danish studies. But expectant mothers who miss sipping the occasional cocktail should not necessarily raise a glass to toast the results.
While the research indicates that strict abstinence may not be necessary during early to mid pregnancy, the authors say their findings need to be investigated further. Mothers-to-be, they say, should continue to follow current guidelines that advise against any alcohol consumption.
The studies, which were funded in large part by the CDC, involved more than 1,600 women whose average age was about 31. Half of them were first-time mothers, and nearly a third were current smokers. One in eight was a single mother.
The researchers found that 5-year-old children whose mothers drank up to eight alcoholic beverages per week performed just as well as the children of abstainers on tests that measured their intelligence, self-control, and how well they are able to pay attention, plan, and organize.
Drinking more than that may cause harm, however. According to one of the studies, the children of women who drank nine or more drinks per week had shorter attention spans than the children of more moderate drinkers.
Binge drinking, which the researchers describe as five or more drinks on a given occasion, had no significant impact -- positive or negative -- on the children's brain functions. But guidelines would of course recommend strongly against this for any woman, pregnant or not.
The studies were published in BJOG: An International Journal of Obstetrics and Gynaecology.
National Center for Learning Disabilities: "What Is Executive Function?"
National Institute on Alcohol Abuse and Alcoholism: "What Is a Standard Drink?"
CDC: "Unplanned Pregnancy Prevention."
U.S. Experts Respond to Findings
"I'm not at all surprised by these findings," says Karin Blakemore, MD, a professor of gynecology and obstetrics at the Johns Hopkins University School of Medicine in Baltimore. "The evidence suggests, and it has always suggested, that low levels of alcohol do not cause discernible harm."
Blakemore, who was not involved in the research, tells her pregnant patients that the occasional glass or half glass of wine is fine, but she acknowledges that other clinicians may offer different advice.
"Other physicians may say you can drink more, still others may say, 'never, never, never,'" says Blakemore. "It's kind of a tricky thing, because you can't prove what is a safe level."
Aaron Caughey, MD, PhD, is one physician who says never.
"Alcohol offers no benefits to the pregnancy or to you," Caughey, who chairs the department of obstetrics and gynecology at Oregon Health and Sciences University in Portland, tells his patients.
Though the studies show that alcohol does not cause a significant level of harm among a large population, he says, that won't matter to the individual who proves to be the exception and whose child suffers as a result.
In addition to neurodevelopmental problems, drinking during pregnancy can contribute to low body weight, growth problems, poor coordination, abnormal facial features, and other lifelong problems associated with fetal alcohol spectrum disorders (FASD), according to the CDC. Drinking can also raise the risk of miscarriage and stillbirth.
"There is no known safe amount of alcohol to drink while pregnant," the CDC's web site states.
For women who drank before realizing they were pregnant, Caughey says that, in all likelihood, the baby will be just fine. Choosing to drink while pregnant, he says, potentially invites trouble.
"It just doesn't seem worth it," Caughey says of having even a small amount of alcohol while expecting a child. "The science is just not there to say there will be no risk."