Like most people, we Americans adore what caffeine does—it gives us that jolt from a Coke, that mild kick from a Hershey’s bar, that boost from a coffee break. No wonder the average American adult consumes 200 milligrams of caffeine daily, almost 75 percent of it from coffee, and the rest from tea (15 percent), soft drinks (10 percent) and chocolate (2 percent), according to the Center for Science in the Public Interest, a nonprofit group in Washington, D.C. Even pregnant women who deny themselves champagne or cigarettes hesitate to give up their beloved morning cup of coffee. But however socially acceptable and seemingly safe, caffeine is a mildly addictive drug.
No study has shown that caffeine causes birth defects, but neither is it pregnancy-friendly. Research reported in the New England Journal of Medicine found double the risk of miscarriage in women who consumed 1,000 milligrams of caffeine a day, compared with those who consumed very low levels. And a study in Obstetrics & Gynecology found an association between miscarriage and an enzyme involved in caffeine metabolism.
If you have trouble sleeping, caffeine can make this worse, since it is metabolized more slowly as pregnancy progresses. “In the average adult, half the caffeine consumed lingers in the body for 3.5 hours,” says Bennett Alan Weinberg, co-author with Bonnie K. Bealer of The World of Caffeine: The Science and Culture of the World’s Most Popular Drug (Routledge, 2001). “Late in pregnancy, its half-life is closer to 18 hours.”
Experts say moderate amounts of caffeine—usually described as three cups of coffee daily—are safe, but tracking intake is difficult. Researchers assume that a cup contains 100 milligrams of caffeine, says Weinberg, “but people don’t drink coffee in a lab. Content depends on serving size, preparation, type of bean, even the way it’s roasted and ground. Five ounces of weak coffee made with gourmet, dark-roasted beans may contain 50 milligrams, while 12 ounces of French-press coffee made with lightly roasted commercial beans might contain more than 350 milligrams.”
That’s one reason to abstain. Here’s more: Caffeine crosses the placenta to the fetus, which lacks the enzyme needed to metabolize it. Furthermore, most American babies are born with at least some caffeine in their blood. In one extreme case, caffeine withdrawal was suspected in eight newborns whose moms were heavy users of caffeine during pregnancy. After birth, these infants exhibited tremulousness, irritability and vomiting. Their symptoms disappeared in a week, and they proceeded to develop normally. Still, it couldn’t have been fun to start life as a recovering caffeine addict. To protect your baby from having to kick the habit: