By Judy George

Women with a history of migraine had higher risks of pregnancy complications, data from the large prospective Nurses' Health Study II showed.

In models adjusted for age, adiposity, and behavioral and health factors, women with pre-pregnancy migraine had higher risks of preterm delivery (relative risk [RR] 1.17, 95% CI 1.05-1.30), gestational hypertension (RR 1.28, 95% CI 1.11-1.48), and preeclampsia (RR 1.40, 95% CI 1.19-1.65) compared with women who didn't have pre-pregnancy migraine, reported Alexandra Purdue-Smithe, PhD, of Brigham and Women's Hospital in Boston.

Compared with women without pre-pregnancy migraine, risk of preeclampsia was higher among those who had migraine with aura (RR 1.51, 95% CI 1.22-1.88) versus migraine without aura (RR 1.29, 95% CI 1.04-1.61), Purdue-Smithe said during a presentation at a 2022 Neurology meeting, held online and in Seattle. Risks of other adverse pregnancy outcomes did not differ by aura phenotype.

"Migraine is highly prevalent among women of reproductive age and pregnancy complications like preeclampsia, although rare overall, can be life-threatening to the mother and baby," said Purdue-Smithe.

"Our findings suggest that migraine history before the pregnancy portends a heightened risk of preeclampsia and other complications and may be a clinically important factor for physicians to consider when evaluating and managing obstetric risks," she added.

Migraine occurs in about 12% of the U.S. population overall, including 18% of women and 6% of men each year. Migraine and adverse pregnancy outcomes share common pathophysiology, and both are associated with coronary heart disease and stroke, Purdue-Smithe noted.

Some case-control and retrospective studies have suggested that migraine and adverse pregnancy outcomes may be linked, but large prospective studies are lacking, she pointed out. Earlier prospective studies also haven't included information about aura, the migraine phenotype most strongly associated with vascular risk, she added.

Epidemiology studies show that women with migraine often experience a significant improvement in headaches during pregnancy. But recent data from the American Registry for Migraine Research have indicated that about 20% of women with migraine have avoided pregnancy because they believe migraine will worsen during pregnancy, make their pregnancy difficult, or have negative effects on their child.

In their study, Purdue-Smithe and colleagues evaluated 30,555 pregnancies among women in the longitudinal Nurses' Health Study II from 1989 to 2009. They assessed preterm delivery (defined as a baby born before 37 weeks' gestation), gestational diabetes, gestational high blood pressure, preeclampsia, and low birth weight (defined as under 5.5 lb). Log-binomial regression accounted for multiple pregnancies per woman.

Overall, 11% of participants said they were diagnosed with migraine before pregnancy. Pre-pregnancy migraine was not associated with low birth weight (RR 0.99, 95% CI 0.85-1.16) or gestational diabetes (RR 1.05, 95% CI 0.91-1.22).

Although migraine history was reported prior to pregnancy, information about migraine aura was not collected until later in the study, after many of the pregnancies ended, the researchers acknowledged. The study also did not report migraine frequency or other migraine features.