CGRP Migraine Antibodies: What Is the Miscarriage Risk?

What did the study find about migraine antibodies and miscarriage?

Published October 12 in JAMA Neurology, the retrospective study examined pregnancies among people with migraine using US insurance data from 2018–2021. The adjusted hazard ratio for anti-CGRP antibodies was 1.42, with a 95% confidence interval of 1.12–1.80. [Study abstract](https://pubmed.ncbi.nlm.nih.gov/42862583/).

This is a relative comparison over follow-up, not an individual's absolute probability of miscarriage. Treatment was not randomly assigned, leaving uncertainty about other differences between patients. The propranolol finding also does not establish that this alternative is suitable for every pregnancy.

Why are researchers concerned about blocking CGRP during pregnancy?

These preventive treatments target calcitonin gene-related peptide, or CGRP, signaling: erenumab blocks its receptor, while fremanezumab, galcanezumab and eptinezumab target the peptide itself. Although this pathway is useful for treating migraine, it also participates in pregnancy physiology. The European Headache Federation identifies this overlap as a reason for caution; a plausible mechanism alone does not prove harm in humans. [European Headache Federation guideline](https://pmc.ncbi.nlm.nih.gov/articles/PMC9188162/).

Earlier evidence was less conclusive. A 2023 analysis of pregnancy reports in the World Health Organization's VigiBase database found no overall signal of increased miscarriage reporting for these antibodies. However, spontaneous reports lack a reliable count of all exposed pregnancies and can contain missing information. They therefore cannot establish miscarriage incidence or rule out a risk that a different study design might detect. [VigiBase analysis](https://journals.sagepub.com/doi/10.1177/03331024231158083).

How should patients plan migraine treatment around pregnancy?

The European Headache Federation's 2022 guidance already suggested avoiding CGRP monoclonal antibodies during pregnancy and breastfeeding. These medicines remain in circulation for months; the guideline discusses approximately six months after discontinuation before they are considered eliminated. That makes advance planning useful, although timing and replacement treatment require an individualized discussion. [European Headache Federation guideline](https://pmc.ncbi.nlm.nih.gov/articles/PMC9188162/).

A medication review should address both prevention and treatment of attacks. The American College of Obstetricians and Gynecologists advises reviewing preventive headache medicines during pregnancy and adjusting them when appropriate. Its patient guidance identifies acetaminophen as an option for headache pain and metoclopramide as a prescription option in selected circumstances. These treatments serve different purposes from long-term prevention, so replacing an injection with an occasional pain medicine may leave important needs unmet. [ACOG headache guidance](https://www.acog.org/womens-health/faqs/headaches-and-pregnancy).