Background Subarachnoid hemorrhage (SAH) in pregnancy occurs because of a variety of etiologies, which range from ruptured aneurysms to benign venous bleeding. The more malignant etiologies represent an important cause of maternal morbidity and mortality. We sought to investigate the epidemiology and mechanisms of pregnancy-related SAH. Methods Using the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality, we extracted pregnancy-related admissions for women ages 15-44 from 1995-2008 and identified admissions complicated by SAH. Logistic regression identified independent predictors of SAH. Outcomes and risk factors were then compared with age-matched, nonpregnant women with SAH. We also analyzed our institution's experience with pregnancy-related SAH. Results There were 639 cases (5.8 per 100,000 deliveries) of pregnancy-related SAH in the cohort during the study period; SAH was associated with 4.1% of all pregnancy-related in-hospital deaths. More than half of the SAH cases occurred postpartum. Advancing age, African-American race, Hispanic ethnicity, hypertensive disorders, coagulopathy, tobacco, drug or alcohol abuse, intracranial venous thrombosis, sickle cell disease, and hypercoagulability were independent risk factors for pregnancy-related SAH. Compared with SAH in nonpregnant controls, pregnancy-related SAH had lower clipping/coiling rates (12.7% vs. 44.5%, P < 0.001). We identified 12 cases of pregnancy-related SAH in our hospital, the majority of which presented postpartum and with severe headache. Conclusion SAH during pregnancy results from a range of etiologies, and is less likely to be because of a cerebral aneurysm than SAH occurring in the nonpregnant patient. Peripartum SAH frequently occurs in the setting of hypertensive disorders.