New Study Finds Caffeine Can Lead to Miscarriage
Pregnant women who regularly drink caffeinated coffee, tea, soda or hot chocolate are at a much higher risk of miscarriage, according to a new study that provides the best evidence yet of a link between the two.

The study, conducted by health insurer Kaiser Permanente’s Division of Research, finds that women who consume 200 milligrams or more of caffeine per day – that’s two or more 5-ounce cups of coffee or five 12-ounce cans of caffeinated soda – are twice as likely to miscarry as women who consume no caffeine. Women who consume less than 200 milligrams of caffeine daily have more than a 40 percent increased risk of miscarriage.

The study looked at 1,063 pregnant Kaiser Permanente members in San Francisco from October 1996 through October 1998. Previous research had shown a link between caffeine and miscarriage, but critics claimed those findings did not take into account the fact that many healthy pregnant women reduce their intake of caffeine because of nausea, vomiting and an aversion to caffeine.

The Kaiser study controlled for morning sickness by looking at caffeine’s effects among women who never changed their pattern of caffeine consumption during their pregnancy. So the findings are considered more conclusive.

Health experts suspect that caffeine can cross through the placenta to the fetus, which would have difficulty metabolizing it. Experts say caffeine may also affect cell development and decrease placental blood flow, and that all of this can lead to miscarriage.

Researchers’ advice?

“The main message for pregnant women from these findings is that they probably should consider stopping caffeine consumption during pregnancy,” study researcher De-Kun Li, M.D., Ph.D., said in a press release on the findings.

Tracy Flanagan, M.D., director of women’s health at Kaiser Permanente Northern California, took a more moderate stance: “If you definitely need caffeine to get you going, try keeping it to one cup or less a day. Avoiding it may be even better.”

Flanagan advised learning to “perk up” instead with natural energy boosts such as a brisk walk, yoga or eating dried fruits and nuts.

– Deirdre Wilson

Posted January 2008.