Study links CGRP antibodies to approximately 40% higher miscarriage risk — ScienceAlert

An observational study of US insurance data found an association between exposure to monoclonal antibodies targeting the CGRP peptide and an approximately 40% higher likelihood of miscarriage during the first 20 weeks of pregnancy. The study does not prove that these drugs themselves cause miscarriage.

What data were analyzed

As ScienceAlert reports, a team led by epidemiologist Anick Bérard of Canada’s Centre Hospitalier Universitaire Sainte-Justine analyzed the first 20 weeks of 7,579 pregnancies. The data were provided by private health insurers in the United States for 2018–2021.

Women diagnosed with migraine or those who had been prescribed triptans or ergot drugs during the six months before their last menstrual period were included in the sample. Some of them were prescribed CGRP antibodies — erenumab, fremanezumab, galcanezumab, or eptinezumab — during pregnancy or in the six months before it. The researchers also assessed exposure to propranolol using the estimated number of days of therapy exposure.

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According to the results, exposure to anti-CGRP antibodies was associated with an increased risk of miscarriage, while no such association was found for propranolol. These drugs are used to prevent migraines, including as an option for patients who are not helped by common oral medications.

Study limitations

The authors stressed that this is a statistical association, not an established causal effect of the medications. CGRP antibodies are generally prescribed for severe or treatment-resistant migraine, so characteristics of the disease itself could also have potentially influenced the result.

Insurance records did not contain data on migraine severity, did not confirm whether prescribed medicines were actually taken, and did not indicate whether the pregnancy was planned. In addition, the sample included only commercially insured people in the United States, so the conclusions may not apply to other population groups or other countries. The study was published in the journal JAMA Neurology.