It is concluded from a review of the literature and a pilot survey that schizophrenic patients more frequently have a history of obstetric complications (OCs) than do other psychiatric patients and normal subjects. OCs are associated with increased cerebral ventricular size in both infancy and adulthood, and are more common among non-familial schizophrenic patients. Neonatal cerebrovascular events consequent upon OCs provide a mechanism to explain the increased risk of neurodevelopmental deviance and later schizophrenia.