Pregnant women who used anti-CGRP monoclonal antibodies early in pregnancy for migraine prevention had a higher risk of spontaneous abortion, according to a retrospective U.S. cohort study reported by MedPage Today. The study drew on the AM-PREGNANT cohort, built from commercial insurance claims from 2018 to 2021, and included 7,119 women with pregestational migraine and 7,579 singleton pregnancies.
Exposure to erenumab, fremanezumab, galcanezumab, or eptinezumab was associated with a 42% higher risk of spontaneous abortion at 20 weeks or less compared with no exposure. By contrast, propranolol was not associated with increased risk. The researchers pointed to CGRP's role in vascular regulation, implantation, placental development, and uteroplacental blood flow as a plausible reason for the safety concern.
The authors said the findings align with current guidelines recommending that women stop anti-CGRP monoclonal antibodies at least five months before conception and switch to established preventive therapies such as propranolol. Limitations include reliance on prescription records, unknown pregnancy intention, possible residual confounding by migraine severity, and a commercially insured population that may not represent all U.S. patients.