Mifepristone-related foetal cardiac adverse events: findings from the postmarketing safety reports.

Background: This study aimed to analyse the clinical characteristics of mifepristone-associated congenital and foetal cardiac adverse events using data from the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS).

Methods: A retrospective pharmacovigilance analysis was conducted using FAERS data from Q1 2016 to Q4 2022. Disproportionality analysis was performed using the Bayesian Information Component (IC) to detect potential associations between mifepristone and congenital or foetal cardiac adverse events.

Results: A total of 1,130 reports involving mifepristone were identified, of which 18 (1.59%) were related to congenital or foetal cardiac events. Most reports originated from the United States. The most frequently reported events were foetal arrhythmia and foetal heart rate disorder. Notably, foetal arrhythmia showed the strongest signal (IC = 3.13, CI₀₂₅ = 1.37). No disproportional signals were detected for structural cardiac malformations. A partial assessment of the Bradford Hill criteria suggested a possible association with functional cardiac anomalies.

Conclusion: This study did not identify an association between mifepristone exposure and structural congenital heart defects. However, a positive signal for transient foetal heart rhythm abnormalities was observed. Clinicians should remain vigilant for foetal heart rate irregularities following maternal mifepristone use and consider enhanced cardiac monitoring during labour and delivery to enable early detection and management.