Contemporary management of migrainous disorders in pregnancy
Association with pregnancy
Over 90% of patients with headache during pregnancy have a pre-existing headache and less than 10% of patients develop new-onset headache during pregnancy [4]. Hormonal and vascular changes of pregnancy may influence the new onset of headache. Among those with pre-existing headache, over 80% are migraine and of those with new-onset headache, one-third is migraine and one-third is related to hypertension [4]. New-onset secondary headache in pregnancy is related to stroke and central venous thrombosis, arterio-venous malformations, brain tumors and benign intracranial hypertension [6]. Pregnant patients with new-onset migraine, pain that is worsening or that is different from usual migraines, with seizures, papilledema, or focal neurological signs or symptoms require a complete neurological evaluation since these characteristics are suggestive of secondary causes of headaches.
Approximately 50–80% of migraine and 30% of tension-type headache patients report improvement of symptoms during the third trimester [6–8]. Less than 30% of patients whose headache has not improved by the second trimester are likely to experience significant improvement throughout the rest of pregnancy [9]. Approximately half of patients experiencing relief during pregnancy will have a recurrence by 1 month postpartum [10].
Patient characteristics
Factors that are significantly associated with a complaint of migraine during pregnancy are a pregestational body mass index (BMI) of greater than 25 kg/m2, less than 5 h of sleep per night, unemployment, depression, sick leave during pregnancy, asthma, hypertension and discontinuation of serotonin-reuptake inhibitors.
Association with other medical conditions
There are several case-control and large cohort studies supporting an approximately two-fold increase in the incidence of preeclampsia among pregnant migraineurs. One case control study reported a higher frequency of chronic migraine among eclamptic compared to noneclamptic patients. This relationship was not seen for tension-type headaches [19]. Migraine with aura has been associated with a small increase in the absolute risk for stroke [20] and a significant increase in the relative risk for pregnancy related stroke [21].
Therapy
Preconceptional counseling regarding therapy for migraine headaches should be established to avoid unwanted fetal exposure to medications that have a potential teratogenic effect. If a patient is using pharmacotherapy and not using effective contraception, it is preferable to use a medication that is well tolerated during pregnancy.
Treatment categories
Although many pregnant women with mild headache will not require medication for pain management, approximately 70% of patients will require some form of intervention. The focus of therapy should be aggressive management of nausea, avoidance of nicotine, adequate hydration and sleep. When pharmacotherapy is required it should be tapered down to the lowest dose necessary for symptom control.
Behavior modification and physical therapy
Of the various alternative options for management of migraine, only relaxation and biofeedback have been shown to be effective during pregnancy [22]. Other alternative forms of therapy include lifestyle changes, physical therapy and exercise [40,41]. Lifestyle changes that could potentially impact outcome are adequate sleep, regular meals, and avoidance of nicotine.
Other alternative forms of management for migraine headache that are reported in the literature include closure of a patent foramen ovale [43]; however, this has not conclusively been shown to be effective [44] and its use for this purpose during pregnancy is not recommended.