Congenital and Fetal Effects After Mifepristone Exposure and Continuation of Pregnancy: A Systematic Review

Mifepristone is an anti-progestational drug that is the first component of the standard medical abortion regimen. For women who take mifepristone and then do not take misoprostol, which is the second component of the medical abortion regimen, it is possible that their pregnancy may continue to live birth. Since mifepristone is commonly used for medical abortion up to 9–10 weeks gestation, any adverse or teratogenic effects on the developing embryo/fetus must be considered, given exposure during the critical time of its development and organogenesis. Toxicology and teratology reports have cited studies demonstrating teratogenic effect of mifepristone in some animals. Current clinical guidelines for women exposed to mifepristone in the first trimester of pregnancy state that it is not known to be teratogenic based on limited published evidence from humans. The aim of this narrative systematic review was to investigate embryonic/fetal exposure to mifepristone and any association with congenital or fetal anomalies. This study was conducted by systematic searches of health databases from inception to February 2024. The references of relevant citations were manually searched to retrieve any additional citations not captured in database searching. Congenital anomalies and adverse outcomes were encountered at various doses of mifepristone exposure. A number of the congenital anomalies encountered in this review were explained by circumstances other than exposure to mifepristone. The present systematic review did not find data to support mifepristone being implicated as a teratogen.