Researchers have found colchicine, a potentially fatal plant extract, in the blood of pregnant women taking gingko biloba. Colchicine is not normally found in humans but is found in more than 200 plants. Researchers have long known that colchicine in small doses can be an effective anti-inflammatory agent. However, colchicine can be fatal if taken in high doses.

The researchers believe the compound found in the pregnant women's placental blood originated from the commercial gingko biloba supplements the women were taking. The researchers, whose study will be published in the journal Chemical Research in Toxicology, note that there is no specific evidence linking colchicine with birth defects.

This is the first time colchicine has been found in the placenta, the sac that surrounds the fetus. Researchers took placental blood samples from more than 20 new mothers. Several of these women were regularly taking gingko supplements and had colchicine in their blood. The remaining women had virtually no traces of the compound in their blood.

The U.S. Food and Drug Administration does not regulate gingko supplements because they are considered herbal medicines.