Traditionally doctors have told pregnant women they can have coffee in moderation.
Time to revise that thought according to the latest research.
It shows that having caffeinated coffee during pregnancy, particularly more than two cups of coffee daily, nearly doubled the risk of miscarriage when compared to women who did not drink coffee.
Researchers at the Kaiser Permanente Research Division in Oakland followed 1,063 pregnant women throughout their pregnancy monitoring their coffee intake. The numbers were collected from October, 1996 to October 1998.
The study is published in the American Journal of Obstetrics and Gynecology.
Soda drinkers are not off the hook. Five 12-ounce sodas have about 200 milligrams of caffeine and those women also had an increased risk as did tea and hot chocolate drinkers. Women who consumed less than 200 mg daily still had an increased risk for miscarriage-about 40 percent.
"I am not at all surprised by this study," Dr. Sherman Silber, director of the Infertility Center at St. Lukes Hospital in St. Louis, tells ABC News. "Coffee is toxic stuff."
There is no consensus on the coffee-pregnancy issue. A study published in the journal Epidemiology shows that moderate coffee consumption, two cups or less did not have an increased risk for miscarriage.
Not considered in this story are the affects of caffeine on the developing fetus.
In the blood stream, it increases alertness, blood pressure and anxiety in the woman and has the same affect on the fetus, crossing the placenta to increasing fetal heart rate and breathing. It can be difficult for the fetus to metabolize caffeine because its system is under-developed and caffeine may influence cell development and decrease blood flow.
Other studies have linked coffee consumption to miscarriage but researchers say those studies failed to control for behaviors that might contribute to poor overall health, such as alcohol consumption and smoking.
Another opinion by Dr. Tommaso Falcone, professor and chair of the Department of Obstetrics & Gynecology at the Cleveland Clinic, observes that among 130 of the 172 total miscarriages were women who had little or no coffee consumption. That hardly makes it definitive.
"[This means] that miscarriages can still occur and women should not feel that they caused it by having a cup of coffee," Falcone tells ABC News.
Bottom line – Should doctors advise their pregnant patients to stop drinking coffee altogether? Dr. De-Kun Li, primary study investigator, says yes.
"This is something you can control if you're worried about a miscarriage," Li told ABC News. "There's lots of things we can't control, but this is one thing that you can."
Though Dr. Li admits that how little coffee one can safely consume remains a mystery, doctors might advise their coffee-addicted pregnant patients to cut back to one cup per day. #