Between 40% and 90% of all women in the Western world use at least one medication during pregnancy. Since the thalidomide tragedy, every drug has been viewed as a potential teratogen. In fact, only roughly 20 xenobiotics are proved human teratogens. In a recent study conducted in Toronto, Canada, we showed that women consulting the Motherisk program (an antenatal consultation service for drug, chemical, and radiation exposures) assign themselves a 25% teratogenic risk when exposed to nonteratogenic drugs.
Clearly, there is a need for authoritative information on the risk of exposure to drugs, chemicals, radiation, or infection in pregnancy. Although it is facile to say, "Do not use during pregnancy," more than 50% of the women contacting the Motherisk program do so after realizing that conception occurred while being exposed to the agent in question. For these women, the notion "do not use during pregnancy" may easily translate to "terminate