Approximately one-fourth of the excess cases of maternal stroke associated with migraine were attributable to hypertensive disorders.
Gretchen Bandoli, PhD
Results from a retrospective birth cohort of 3 million singleton, live births between January 2007 to December 2012, revealed an increased risk of having a hypertensive disorder, a stroke during pregnancy, or post-partum stroke in women with migraines during pregnancy.
Overall, the study found 26,440 women with a diagnosis of migraine (914 of 100,000 deliveries) and 843 women who suffered from stroke (29 of 100,000 deliveries). More specifically, 58% of all stroke events were ischemic, 11 women had strokes during pregnancy and at delivery, and 29 women had strokes during pregnancy/delivery at the post-partum period.
Research led by corresponding author Gretchen Bandoli, PhD, assistant professor, department of pediatrics, University of California, showed that women with migraines during pregnancy were more likely to have a hypertensive disorder (15.1% vs 7.0%; adjusted risk ratio [aRR], 1.6%; 95% CI, 1.6–1.7), a stroke during pregnancy or delivery (0.15% vs 0.01%; aRR, 6.8; 95% CI, 4.7–9.8), or stroke post-partum (0.05 vs 0.01; aRR, 2.1; 95% CI, 1.2–3.7).
“Approximately one-fourth of the excess cases of maternal stroke associated with migraine were attributable to hypertensive disorders. This suggests that other pathways exist between migraine and stroke during the perinatal period, potentially through pathophysiologic changes, such as increased blood volume and cerebral circulation,” Bandoli and colleagues concluded.
Demographically, women with migraines were more likely to be non-Hispanic white, have private insurance, have obesity, have diabetes (preexisting or gestational), have a mental health disorder, use tobacco, and/or use drugs or alcohol.
Hypertensive disorders mediated 21% of the risk of stroke during pregnancy and delivery and 27% of the risk of post-partum stroke when observed in a mediation analysis adjusted for the same potential cofounders. Additionally, although the data was not included, researchers noted that despite small numbers, the effects were twice as strong in models for ischemic stroke compared with hemorrhage stroke.
Multivariable log-linear regression, adjusting for age, body mass index (BMI, calculated as weight in kilograms divided by height in meters squared), race/ethnicity, nativity, payer source, mental illness, smoking, drug or alcohol use, and diabetes were all used to estimate the association between migraine and stroke.
The proportion of the total association of migraine with the risk of maternal stroke mediated by gestational hypertensive disorders was estimated using a mediation analysis. Researchers concluded that approximately 25% of the excess risk of maternal stroke associated with migraine was mediated through hypertensive disorders. They added “Although strokes are rare events, the associated morbidity and mortality warrants focus on identifying modifiable intervention targets.”
Bandoli G, Baer RJ, Gano D, Pawlowski LJ, Chambers C. Migraines during pregnancy and the risk of maternal stroke. JAMA Neurol. Published online June 1, 2020. doi: 10.1001/jamaneurol.2020.1435