From 1957 to 1962, an epidemic of about 4000 cases of phocomelia, a severe, congenital malformation of deformed or rudimentary limbs, occurred from in utero fetal exposure to thalidomide1 after its administration to pregnant mothers to treat nausea and vomiting or anxiety during the first trimester of pregnancy, even though thalidomide had been shown to be safe and efficacious in both nonpregnant laboratory animals and nonpregnant subjects enrolled in clinical trials.2 The medical community therefore codified through the United States Food and Drug Administration Drug Regulation Act of 1962 that the safety of drugs during pregnancy cannot be extrapolated from clinical studies in nonpregnant patients, but must be demonstrated directly by clinical studies in pregnant patients.