Intracranial hemorrhage from aneurysms and arteriovenous malformations during pregnancy and the puerperium. Intracranial hemorrhage (ICH) from an intracranial aneurysm or arteriovenous malformation is a grave complication of pregnancy and is responsible for 5 to 12% of all maternal deaths. We critically analyzed 154 cases of verified ICH during pregnancy from an identified intracranial lesion, including 2 patients treated at our institution and 152 cases previously reported in the literature in English. Aneurysms were responsible for ICH in 77% of patients, and arteriovenous malformations in 23%. Hemorrhage occurred antepartum in 92% of patients and postpartum in 8%. Women with angiomatous hemorrhage were younger than those with aneurysmal hemorrhage; however, in contrast to previous reports, we found no differences between angiomatous and aneurysmal hemorrhage with respect to parity or gestational age at the time of the initial hemorrhage. Hypertension and/or albuminuria were present at some time during the pregnancy in 34% of patients with documentation, which sometimes made it difficult to differentiate angiomatous or aneurysmal ICH from that associated with eclampsia. In a logistic regression analysis, surgical management of aneurysms, but not arteriovenous malformations, was associated with significantly lower maternal and fetal mortality, independent of other covariants. For those patients with a lesion not operated on, cesarean delivery afforded no better maternal or fetal outcome than did vaginal delivery. We conclude that the decision to operate after ICH during pregnancy should be based upon neurosurgical principles, whereas the method of delivery should be based upon obstetrical considerations. The perioperative and anesthetic management of the pregnant patient with a neurosurgical complication is discussed. 