Final results from the ribavirin pregnancy registry, 2004-2020

Introduction: Significant teratogenic effects have been demonstrated for ribavirin in animal studies. Ribavirin is prescribed for chronic hepatitis C and is contraindicated in pregnant women and their male sexual partners. Both are advised to avoid pregnancy for 6 months after exposure. The registry monitored pregnancy exposures to oral formulations of ribavirin for hepatitis C for signals of possible human teratogenicity from 2004 to 2020. Methods: Pregnant women were voluntarily enrolled following direct exposure (ribavirin use during pregnancy or the 6 months prior) or indirect exposure (through sexual contact during pregnancy or 6 months prior, with a man who has taken ribavirin within 6 months). Women were followed until the end of pregnancy. Infants were followed until 1 year of age. Birth defect rates were compared with the published rate of 2.67 per 100 live births from the Metropolitan Atlanta Congenital Defects Program (MACDP). Results: The registry enrolled 280 pregnancies resulting in 186 live births: eight birth defect cases among 88 directly exposed [9.09% (8/88, 95% CI: 4.01, 17.13)], and six birth defect cases among 98 indirectly exposed [6.12% (6/98, 95% CI: 2.28, 12.85)]. The 95% CI around the birth defect rate among directly exposed pregnancies exceeds the MACDP rate; however, no patterns suggestive of a teratogenic mechanism or safety signal were detected. Conclusion: Based on the patterns of birth defects reported, the final results from this registry do not suggest a clear signal of human teratogenicity for ribavirin. The registry did not meet sample size requirements; therefore, caution should be exercised when interpreting the results.