Background Migraine is a neurovascular disorder most prevalent among women 18-45 years old (~25%). No prospective studies have examined associations of migraine and aura phenotype with spontaneous abortion, stillbirth, or ectopic pregnancy.

Methods We estimated associations of self-reported physician-diagnosed migraine before pregnancy (14%) and aura phenotype with spontaneous abortion (losses <20 weeks), stillbirth (losses ≥20 weeks), and ectopic pregnancy among incident pregnancies in the prospective Nurses’ Health Study II (n=40,339). Relative risks (RR) and 95% confidence intervals (CI) were estimated using log-binomial regression that accounted for multiple pregnancies per participant.

Results In adjusted models, migraine was modestly associated with overall risk of spontaneous abortion (RR=1.08; 95% CI=1.02-1.15). This association was more prominent for losses occurring during 12-19 weeks’ gestation (RR=1.15; 95% CI=1.01-1.32) than earlier losses (<8 weeks RR=1.04; 95% CI=0.92-1.17; 8-11 weeks RR=1.06; 95% CI=0.95-1.18). The overall risk of spontaneous abortion appeared slightly stronger for migraine with aura (RR=1.12; 95% CI=1.03-1.22) than without aura (RR=1.04; 95% CI=0.96-1.13), compared to no migraine. Migraine was not significantly associated with stillbirth (RR=1.14; 95% CI=0.86-1.52) or ectopic pregnancy (RR=1.31; 95% CI=0.97-1.76), though power for these analyses was limited.

Conclusions Migraine is associated with a modestly higher risk of spontaneous abortion, especially later in gestation.