PURPOSE:

• There is literature to suggest a relationship between migraine headaches and peripartum maternal stroke
• While this association is likely due to hypertensive disorders of pregnancy, data remains limited
• Bandoli et al. (JAMA Neurology) sought to determine if hypertensive disorders in pregnancy is the connection between migraine and maternal stroke

METHODS:

• Retrospective Cohort Study
  • California birth cohort analyzed (2007 to 2012) | 3 million singleton, live births | Based on linked birth certificates and hospital discharge summaries
• Migraine, hypertensive disorders of pregnancy, and stroke identified using ICD9 data 
• Primary outcome
  • Association between migraine and peripartum stroke
• Statistical analysis
  • Multivariable log-linear regression
  • Adjusted for confounders: Age | BMI | Race and ethnicity | Nativity | Payer source | Mental illness | Smoking | Drug or alcohol use | Diabetes
  • Calculation performed to determine the risk of maternal stroke mediated by gestational hypertensive disorders (mediation analysis)

RESULTS:

• Patients with migraine: 26,440
• Patients with strokes: 843 | ischemic strokes comprised 58%

Migraine during pregnancy was associated with increased risk for

• Hypertensive disorder
  • Migraine: 15.1%
  • No Migraine: 7.0%
  • Adjusted risk ratio (aRR) 1.6 (95% CI, 1.6-1.7)
• Stroke during pregnancy or delivery
  • Migraine: 0.15%
  • No Migraine: 0.01%
  • aRR 6.8 (95% CI, 4.7-9.8)
• Postpartum stroke
  • Migraine: 0.05%
  • No migraine: 0.01%; aRR 2.1 (95% CI, 1.2-3.7)
• Ischemic stroke subgroup
  • Effects were twice as strong in models for ischemic stroke compared with hemorrhagic

Mediation analysis for hypertensive disorders (adjusted)

• Hypertensive disorders of pregnancy (mostly preeclampsia) mediated a proportion of stroke risk
  • Stroke (pregnancy/delivery): 21%
  • Postpartum stroke: 27%

CONCLUSION:

• Approximately 25% of strokes in pregnancy that are associated with migraines can be attributed to hypertensive disorders
• Authors acknowledge some significant limitations
  • Errors regarding accurate timing of the events | Migraines could be falsely coded as a result of a stroke rather than predating the event
  • Likely only severe migraines would be documented and therefore relative risks may not apply to more mild presentations
• In addition, the authors state that

Although strokes are rare events, the associated morbidity and mortality warrants focus on identifying modifiable intervention targets

Learn More – Primary Sources:

Migraines During Pregnancy and the Risk of Maternal Stroke

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