Abstract DP151: Subarachnoid Hemorrhage and Cerebral Aneurysm in Pregnancy and Puerperium

Background: The management of unruptured cerebral aneurysms (UCA) during pregnancy is complex, and data on associated subarachnoid hemorrhage (SAH) risk are limited. This study aimed to compare the incidence of SAH during pregnancy and the postpartum period in women with and without UCA, and to assess maternal and fetal outcomes. Methods: We conducted a retrospective cohort study using the COSMOS EPIC database, including pregnancies delivered between January 1, 2016, and January 1, 2024. UCAs and SAH events were identified via ICD-10 codes, with SAH defined as any diagnosis from estimated pregnancy start date to six weeks postpartum. Baseline characteristics were compared using chi-square, t-tests, or Wilcoxon rank-sum tests. Multivariable logistic regression adjusted for clinical covariates evaluated associations between UCA, SAH, and mortality. Propensity score matching (1:1 nearest neighbor, caliper 0.2) balanced baseline variables. Results: Of 5,404,933 pregnancies, 2,770 (0.05%) had a UCA. SAH incidence was significantly higher in the UCA group compared to controls (1.7% vs. 0.008%, p