Migraine headaches often improve during pregnancy, but have also been known to exacerbate, or even commence during this time. Encouragingly almost half of women with migraine have improvement during the first trimester, and this improvement increases significantly in the second (83%) and third (87%) trimesters.

It is important to develop a plan for preconception counselling and migraine treatment during pregnancy. During the preconception visit, plans to discontinue preventative medication prior to conception are discussed. Removal of the migraine preventative may result in increased migraine events, and patients are encouraged to consult additionally with an obstetrician to address any fertility concerns. In addition, it is advised to engage in lifestyle modifications including sleep hygiene, exercise, such as yoga, as well as therapies including biofeedback and acupuncture.

For migraine headache events first line treatment is acetaminophen, in addition caffeine and metoclopramide are advised. Failing this, Sumitriptan is the most studied and preferred choice of triptan during this time. Insufficient data currently exists for the other triptan medications to recommend these alternatives.

If preventative medication needs to be started during pregnancy, severity of disease is considered, with a risk/benefit, and case by case analysis considered. For women with significant disability due to migraine, the risk of medication needs to be weighed against the health consequences of untreated migraine, which can negatively affect the mother and the foetus. Untreated migraines can lead to reduced oral intake, resulting in poor nutrition and dehydration, in addition to lack of sleep, increased stress and risk of depression.

In the first trimester, Greater Occipital Nerve Blocks (GONBs) are the preferred treatment. Second line options include propranolol or amitriptyline. Topiramate (increased risk of cleft palate) and Valproate (known to be associated with neural tube defects and neurodevelopmental disorders), are not safe during pregnancy.

For patients with chronic migraine, who do not respond to GONBs, with significant disability, and who had improvement with OnabotulinumtoxinA prior to pregnancy, recommencement on this therapy is considered. This is supported by a recent retrospective review of 232 women with exposure to OnabotulinumtoxinA 3 months before, or during pregnancy, which did not show an increased risk of foetal abnormalities.

Neuromodulation devices can also be considered, and although specific evaluations of these devices in pregnant women is lacking, encouragingly no foetal malformations or birth defects have been observed.

We often get asked about Calcitonin gene related peptide (CGRP) blocking monoclonal antibodies, recently approved for migraine prevention. These drugs were not however tested during pregnancy. CGRP does have a role in pregnancy vasculature, and the medications are to be avoided during pregnancy until further studies are performed. Given this, it is important, given the long half life with these agents, to discontinue the preparations at least 5 months prior to conception.

Practical Neurology; Kate Onorato MD, Carrie Dougherty MD FAHS, Jessica Ailani MD, FAHS; May 2019