Final results from the ribavirin pregnancy registry, 2004-2020

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.

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).

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.

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.