OnabotulinumtoxinA for chronic migraine during pregnancy: a real world experience on 45 patients

Objective To report the pregnancy outcomes on patients with chronic migraine exposed to onabotulinumtoxinA from Hull Headache Clinic. Background Migraines are common in women of reproductive age and those with chronic migraine have a major impact on their activities of daily living and health-related quality of life. Apart from low dose amitriptyline and beta-blockers all other prophylactic agents have proven teratogenic effects. OnabotulinumtoxinA is approved as preventive treatment for adult patients with chronic migraine, although its impact on pregnancy is unknown. Methods We prospectively collected data for efficacy and safety on all patients treated with onabotulinumtoxinA at the Hull Headache Clinic. The toxin is administered as per PREEMPT paradigm. Female patients of reproductive age group receiving onabotulinumtoxinA are given advice on contraception and the unknown impact of the toxin on pregnancy. They are asked to report pregnancy when they are appraised on the risk/benefit of treatment continuation. All patients are consented for access to their medical records and pregnancy outcome and those who wished to continue are asked to sign a disclaimer. Pregnancy outcome data was collected on all patients for the mode of delivery, birth weight and congenital malformation and any other unexpected outcomes. Results Over 9 years period 45 patients reported pregnancy while receiving onabotulinumtoxinA. All patients had received onabotulinumtoxinA within 3 months prior to the date of conception. 32 patients wished to continue treatment during pregnancy while the remaining 13 stopped treatment. Apart from 1 miscarriage in the treatment group, all patients had full term healthy babies of normal birth weight and no congenital malformations. Conclusion We report our experience of 45 patients exposed to onabotulinumtoxinA during pregnancy. Although the numbers are small, there was no impact of the toxin found on the pregnancy outcomes.