For the recent study, researchers looked at over 1,000 women from the Kaiser Permanente Medical Care Program in San Francisco. Each woman was interviewed at an average of 10 weeks gestation; 16 percent of the women had miscarriages.
Researchers found that 25 percent of the women who miscarried reported consuming no caffeine during their pregnancy. Another 60 percent said they had up to 200 milligrams of caffeine daily, and 15 percent consumed more than 200 milligrams of caffeine each day.
Dr. Laura Corio of Mount Sinai Medical Center explains, "The problem with this study is that when people miscarry, a large percentage of those miscarriages are due to genetic abnormalities, and the researchers didn't say whether these were normal or abnormal fetuses."
However Corio does advise pregnant patients to be aware of their caffeine consumption. She states, "Have less than 200 milligrams a day" regardless of the source. She adds that caffeine has also been linked to low birth weights and smaller head circumferences.