Acyclovir in Pregnancy Registry. An observational epidemiologic approach.

Observational epidemiologic methods are being used to evaluate the safety of acyclovir in pregnancy. An essential component of this research is the establishment of a baseline expectation of pregnancy outcomes among women with herpes not receiving acyclovir. Continuing studies will be described in this report. To supplement these structured studies, an international case registration study was established. Through the Acyclovir in Pregnancy Registry, all cases of reported prenatal exposures to acyclovir are tracked to ascertain maternal exposure, risk factor, and pregnancy outcome information. The reports originate in all countries where oral acyclovir is marketed; data consolidation and analysis are coordinated at Burroughs Wellcome Co. with the assistance of a government/industry advisory panel. This presentation summarizes provisional data from the prospective reports, including trimester of exposure and reported outcomes of pregnancy. The total number of monitored pregnancies remains too small to support conclusions about the safety of acyclovir during pregnancy at this point. The potential for the registry and other epidemiologic studies to address the safety-in-pregnancy question will be discussed.