Headaches during pregnancy and the risk of subsequent stroke

Abstract Background Primary headache disorder is a known risk factor for stroke in women and usually improves during the first trimester of pregnancy. However, despite this, some women develop headaches during pregnancy (G-HA), and the effect of this headache on subsequent stroke is unknown. In this study, we evaluated the association between G-HA and stroke after delivery in women. Methods Based on the Korean National Health Insurance Service database, we included women hospitalized for delivery between 2012 and 2013. G-HA was defined as a headache diagnosed during pregnancy. Primary outcome was any stroke that occurred during the observational periods from delivery to December 31, 2020. All diseases were identified based on data registered in the database using the International Classification of Disease-10th Revision-Clinical Modification codes. Results Of 906,187 pregnant women, G-HA was found in 56,813 (6.3%). During the observational periods, the G-HA ( +) group had a significantly higher risk of any stroke [adjusted hazard ratio (aHR) = 1.59, 95% confidence interval (CI): 1.30–1.95], ischemic stroke (aHR = 1.50, 95% CI: 1.12–2.01), hemorrhagic stroke (aHR = 1.63, 95% CI: 1.23–2.15), and intracerebral hemorrhage (aHR = 1.63, 95% CI: 1.19–2.23) than the G-HA (-) group. When analyzed considering the interaction with history of headache disorder, G-HA showed a significant association with hemorrhagic stroke, but lost its effect on ischemic stroke. Conclusions We demonstrated that G-HA was associated with subsequent stroke occurrence after delivery. However, the relationship between G-HA and ischemic stroke is mitigated by a history of pre-pregnancy headache disorder.