A cup of coffee a day during pregnancy probably won’t increase a woman’s risk of miscarriage or premature birth, The American College of Obstetricians and Gynecologists said today.

Until recently, studies have had conflicting findings about the effect of moderate caffeine consumption on pregnancy complications.

But, “I think it’s time to comfortably say that it’s okay to have a cup of coffee during pregnancy,” Dr. William Barth, the chair of a College committee which reviewed the evidence, told Reuters Health.

The College’s Committee on Obstetric Practice said that 200 milligrams of caffeine a day, about the amount in a 12-ounce cup of coffee, doesn’t significantly contribute to miscarriages or premature births. That definition of “moderate caffeine consumption” would also include drinking about four 8-ounce cups of tea or more than five 12-ounce cans of soda a day, or eating six or seven dark chocolate bars.

The committee said the evidence was not clear on whether consuming more than 200 mg of caffeine a day might increase pregnancy risks.

The group considered two recent studies, each of which followed more than 1,000 pregnant women. One study, led by Dr. David Savitz of The Mount Sinai Medical Center in New York, found no increased rate of miscarriage for women who consumed low, moderate, or high levels of caffeine at different points in their pregnancy.

In the other, Dr. De-Kun Li and his colleagues at Kaiser Permanente’s Division of Research in Oakland found a higher risk of miscarriage in women who consumed more than 200 mg of caffeine per day, but no extra risk at lower levels.

The committee also pointed to two other studies that found that a mother’s moderate caffeine intake did not make it any more likely she would deliver a baby prematurely.

Research has shown that caffeine is able to cross the placenta, which led to worries that it could cause miscarriage or premature birth. “It’s not inert, it does have drug-like properties,” Savitz, who was not involved in producing the guidelines, told Reuters Health. And, he said, “it justifiably deserves a close look because it’s so widely used.”

In the U.S., about 16 percent of all pregnancies end in miscarriage and about 12 percent of babies are born prematurely.

Previous studies, Barth said, were mixed and unclear about the link between caffeine and pregnancy risks. It was the new findings from large groups of women that allowed the committee to feel confident that moderate caffeine intake was safe, and “try to bring some conclusion to the subject,” he said.

The committee statement goes along with the thinking that caffeine is “not an all-or-nothing sort of thing,” Savitz said. While some women may choose to cut out caffeine altogether during pregnancy, others might care a lot about that daily cup of coffee and just try to cut back a little - and both options are okay, he said.

Li said that while the committee report is balanced, he would recommend erring on the side of safety - even for low levels of caffeine consumption.

The committee’s opinion could help women make choices during pregnancy, Savitz said. “It’s not either shocking or alarmist or changing radically what we thought before,” he said. “But sometimes I think it’s important for authoritative groups to issue these kinds of statements. I think it can be a helpful guideline to physicians and I also think it can be helpful to women themselves.”

SOURCE:  Obstetrics & Gynecology, online July 21, 2010.