New research may once again shift the advice given to pregnant women about the potential risks of a glass of wine or a cup of coffee. Two reports, both from the UK, are the largest and most rigorous studies on low levels of alcohol or caffeine to date. The verdicts? Limited alcohol consumption is not so bad, while regular caffeine intake is worse than we thought.
In the alcohol study, researchers conducted in-person interviews with 12,495 new moms whose babies were 9 months old. Women were asked if they drank during their pregnancy and, if so, how much. At 3 years, children were assessed for inappropriate conduct (atypical hitting, arguing and acting out) and cognitive ability (knowing numbers and letters, and naming colors and shapes).
As expected, the worst outcomes were seen in children whose moms drank heavily while pregnant. But children of light-drinking moms had fewer behavioral or cognitive problems than those of abstinent moms.
The study, published online in October in the International Journal of Epidemiology, defined light drinking as not more than two drinks (a 4-fluid-ounce glass of wine or 10 fluid ounces of weak beer) on a single occasion and not more than two occasions per week. No difference was seen between women who drank once or twice during their pregnancies and those who regularly enjoyed a weekend glass of wine.
Lead author Yvonne Kelly, an epidemiologist at University College London, says that the links between heavy drinking and fetal alcohol syndrome are undisputed but that little is known about light drinking's effects. That has led to conflicting medical advice from two major UK policymakers, with one urging complete abstinence and the other recommending no more than one to two drinks once or twice a week (if women choose to drink) in the second and third trimesters of pregnancy, but none in the first.
In the U.S., the American College of Obstetricians and Gynecologists advises pregnant women to avoid alcohol entirely.
Caffeine's a concern
The news for caffeine is different. In a study of 2,635 mothers-to-be published online this month in the British Medical Journal, researchers saw effects on babies' birth weights when expectant moms consumed daily doses of as low as 100 mg -- the amount in an 8-ounce cup of coffee. Babies born to women consuming more than 200 mg of caffeine a day weighed an average 2.2 ounces less than those born to moms taking in less than 100 mg. More than 300 mg per day led to a 5-ounce average reduction in birth weight.
A few ounces are not a big deal in otherwise healthy, full-term babies, says lead study author Dr. Justin Konje, a professor of obstetrics and gynecology at the University of Leicester, and are less than the deficits seen in babies of smokers. But in very small infants (say, 2 pounds), 5 ounces may significantly affect the baby's health.
The UK Food Standards Agency responded by reducing the recommended limit for caffeine intake in pregnancy from 300 mg to 200 mg per day. Guidelines in the U.S. are not that specific, although the March of Dimes says caffeine should be limited to 200 mg per day, based on a March study of 1,063 pregnant women by Kaiser Permanente researchers. It found that the risk of miscarriage doubled in women who consumed more than 200 mg, compared with those who consumed little to no caffeine.
Tea accounted for 60% of the caffeine consumed by women in the UK study, coffee for 14% and other items -- chocolate, soda, hot cocoa, energy drinks and over-the-counter medications -- for the remaining 26%. In the Kaiser Permanente study, 63% of the caffeine came from coffee.
"As an obstetrician, I would say better not to drink during the pregnancy," says Dr. Michael Ross, chair of obstetrics and gynecology at Harbor-UCLA Medical Center. But if a woman celebrates her birthday with a drink, "that's probably going to have no detrimental effect at all."
Dr. Laura Riley, medical director of labor and delivery at Massachusetts General Hospital in Boston, says she won't change her advice. She acknowledges that the new caffeine study is rigorous, but she doesn't believe a few ounces is anything to worry about.
As for alcohol, she tells patients, "Nine months is a very short period of time for abstinence."