Adverse drug reactions in utero: perspectives on teratogens and strategies for the future.

Many think of an adverse drug reaction (ADR) as an adverse event caused by a medication intended for a given subject. However, as we learned from the thalidomide debacle 50 years ago, some of the most devastating ADRs affect not the subject who takes the medication but rather, in the case of pregnancy exposures, an innocent bystander--the fetus--and the ADRs include birth defects.