Uniformity in diagnosis and classification of hypertension in pregnancy is important for management, comparing investigative reports, as well as future prognosis; generally it is diagnosed by diastolic blood pressure > or = 90 mmHg, and/or systolic > or = 140 mmHg. Precise etiology remains elusive, but investigations have revealed that abnormal placentation, endothelial dysfunction, abnormalities in maternal circulatory adaptations to pregnancy, genetic factors and immunologic agents all play a role in development of the disease. Trials to evaluate various agents to prevent pre-eclampsia have been disappointing, with minimal evidence that aspirin, calcium, or vitamins C or E prevent disease, and no evidence that antihypertensive agents or diuretics do so. Management of the hypertensive gravida is designed to prevent maternal and perinatal morbidity and mortality, including more intense antepartum surveillance, as well as intrapartum magnesium sulfate to prevent seizures, antihypertensive agents (e.g. hydralazine, beta-blockers) to control blood pressure, and continuous fetal monitoring. Prognosis in future gestations is dependent upon timing of the disease in the index pregnancy, severity and classification of the disease.