Background: Migraine is very common in women of childbearing age. Erenumab is a first-in-class anti-CGRP monoclonal antibody with a a favorable efficacy/tolerability profile. However, there are very limited data on its effects during pregnancy.
Case presentation: We report a case of a 37-years-old woman affected by chronic migraine who became pregnant during erenumab treatment. At the time of her first visit at our Unit she was on prophylaxis with sodium valproate 600 mg/day reporting low efficacy (18 headache days/month) and tolerability (weight gain). She had already failed 5 prior preventative treatments. On the same day started erenumab 70 mg, tapering down valproate. Erenumab was rapidly effective, reducing migraine frequency (7 days/month) since the first administration. On the follow-up visit scheduled for the fifth erenumab administration, the patient informed us of her pregnancy, documented by appropriate serological test the day before. Erenumab was immediately stopped. The last erenumab administration was made on 04/07/2019, probably corresponding to the first two weeks of pregnancy. Serological fetal DNA test was normal. During the I pregnancy trimester the frequency of migraine increased up to 10 days/month, markedly improving and progressively disappearing during the II-III trimesters. Migraine attacks started again from the 34th week of pregnancy throughout delivery and breast feeding. No other adverse event or complication occurred during pregnancy. The baby, born by vaginal birth in healthy conditions, developed breastfeeding jaundice which progressively normalized over time.
Conclusions: We document no complications, abnormalities, or adverse events in both the mother and the child, and a physiological normal course of pregnancy, delivery and breastfeeding in the first report of erenumab exposure during pregnancy in a migraine patient. More data from clinical studies and post-marketing surveillance are necessary to confirm our findings.