Monitoring pregnancy outcomes following prenatal drug exposure through prospective pregnancy registries and passive surveillance: a pharmaceutical company commitment.

Objectives: Glaxo Wellcome (G.W.) becomes aware of prenatal exposures to its medications from as early as the clinical trial phase of development. An international process for monitoring prenatal exposure to all G.W. medicines has been developed utilizing a passive surveillance system and, for specific products, pregnancy registries. Additionally, G.W. jointly sponsors the multi-company Antiretroviral and North American Antiepileptic Drug (AED) Pregnancy Registries.Study Design: The registries are observational, case-registration and follow-up studies designed to detect evidence of teratogenicity associated with specific medications. Pregnancies are registered prospectively following prenatal exposure to the registry medication. An advisory committee for each registry reviews data and assists in dissemination of information. Committee members include independent scientists with expertise in fields such as obstetrics, teratology, epidemiology, pediatrics, and the relevant therapeutic areas.Results: The following data are from the prospective first-trimester exposures in each registry. Through December 1996, the proportion of outcomes in the Acyclovir Pregnancy Registry with birth defects (n = 17/505) is 3.4% (95% CI 2.0%, 5.4%). Through March 1997, the proportion of outcomes in the Lamotrigine Pregnancy Registry with birth defects (n = 4/76) is 5.3% (95% CI 1.7%, 13.6%). Through April 1997, the proportion of outcomes in the Sumatriptan Pregnancy Registry with birth defects (n = 5/148) is 3.4% (95% CI 1.3%, 8.1%). The newer Valacyclovir and Bupropion Pregnancy Registries have insufficient data for analysis. None of the registries have provided a risk estimate exceeding that expected in the general population, and no pattern of defects has been observed.Conclusions: The outcomes accumulated to date represent a sample of insufficient size for reaching conclusions regarding the possible teratogenic risk of using these drugs in pregnancy. Data obtained through these registries are shared with the medical community as a supplement to animal toxicology studies and to assist in weighing potential risks and benefits of treatment for individual patients. The success of the registries depends on the continued willingness of the OB/GYN community to notify the registries of prenatal exposures.