Adding to the wealth of conflicting data about caffeine, researchers said Wednesday that women who drink as little as half a cup of coffee a day right before or during pregnancy may raise their risk of miscarriage.
The researchers, led by Dr. Claire Infante-Rivard of McGill University in Montreal, compared 331 women who had miscarried with 993 who had experienced normal pregnancies.Consuming as little as 48 milligrams of caffeine - about the amount in half a cup of coffee - a day during the month before conceiving appeared to boost the miscarriage risk by 29 percent. Consuming the same amount during pregnancy boosted the risk by 15 percent.
Each additional 100 milligrams of caffeine daily boosted the risk an additional 22 percent, the researchers said. That is about the amount of caffeine in eight ounces of coffee, 15 ounces of tea or eight to 15 ounces of soft drinks containing caffeine. It also is found in many over-the-counter pain remedies.
"A reasonable recommendation would be to reduce consumption of caffeine beverages during pregnancy," the researchers wrote in the Journal of the American Medical Association. They stopped short of recommending that women quit altogether.
The study comes 10 months after federal researchers reported that expectant mothers who consumed up to 300 milligrams of caffeine daily had no higher rates of miscarriage or small fetuses. Other studies have yielded conflicting results.
Since 1980, the Food and Drug Administration has recommended that pregnant
women cut down on caffeine, authors of the new study noted. That recommendation was based on animal studies, but most doctors probably advise their patients along those lines, they said.