Molnupiravir (brand name Lagevrio) is a small-molecule antiviral prodrug active against SARS-Cov-2 and in one trial was found to reduce risk of hospitalization or death from COVID by 52% (Jayk Bernal et al 2022. PMID 34914868).
According to the New York Times:
Molnupiravir cannot be used during pregnancy because of the potential harm to the fetus. For this reason, doctors may also recommend that sexually active men and women of childbearing age use contraception during treatment and for a period afterward (three months for men and four days for women).
Based on findings from animal reproduction studies, LAGEVRIO may cause fetal harm when administered to pregnant individuals.
It also mentions:
While the risk is regarded as low, nonclinical studies to fully assess the potential for LAGEVRIO to affect offspring of treated males have not been completed. Advise sexually active individuals with partners of childbearing potential to use a reliable method of contraception correctly and consistently during treatment and for at least 3 months after the last dose of LAGEVRIO.The risk beyond three months after the last dose of LAGEVRIO is unknown. Studies to understand the risk beyond three months are ongoing.
As an article from Forbes notes:
Reporters have asked the manufacturers about potential mutagenic effects, which Merck has answered by saying that, “the drug will be safe if used as intended and at the concentrations where we have looked and in the concentrations which we are achieving in patients.”