Pregnancy outcome after exposure to ranitidine and other H2- blockers - A collaborative study of the European Network of Teratology Information Services

BACKGROUND: Published data on pregnancy outcome after exposure to H2-blockers is scarce. The aim of the present study was to evaluate the data collected by the memberships of the European Network of Teratology Information Services (ENTIS). METHODS: The patients were pregnant women who or whose doctor or midwife did contact a Teratology Information Service for risk assessment after the use of a H2-blocker in pregnancy. The data were prospectively collected, i.e. before the outcome of pregnancy was known. Standardized procedures for data collection were used by each centre. The data of the exposed women were compared to those of a control group exposed to non-teratogenic substances. RESULTS: Data on the outcome of 553 pregnancies with exposure to an H2-blocker were evaluated (ranitidine n=335; cimetidine n=113, famotidine n=75; nizatidine n=15, roxatidine n=15). Most of them had been exposed at least in the first trimester. The incidence of premature deliveries was higher in the exposed group compared to the control group. There was no increase in the incidence of major malformations. Two pregnancies with maternal use of famotidine in early pregnancy were terminated after the prenatal diagnosis of a neural tube defect. CONCLUSION: There is no indication for an increased risk of major malformations after the use of H2-blockers during pregnancy.