The early recognition of elevated blood pressure in pregnancy is still considered the most critical step in preventing the maternal and perinatal morbidity and mortality associated with preeclampsia–eclampsia. The recognition of hypertension is enhanced by an initial assessment of a woman's risk for developing high blood pressure during pregnancy, correct blood pressure measurement, and early prenatal care. The care of the woman with hypertension preceding a pregnancy or during a previous pregnancy includes not only early prenatal care but also pre- or interconceptual care that might minimize the risk of further blood pressure elevation during pregnancy, as well as later in life. Tests to predict preeclampsia, such as the “roll” test and the use of the mean arterial pressure during midpregnancy, have been found to be invalid because of poor predictive validity. Relative increases in blood pressure during pregnancy are also no longer considered diagnostic for preeclampsia, however, consideration of relative increases is still “prudent” in assessing signs and symptoms of this disease. The development of preeclampsia is thought to occur very early in pregnancy as a result of imbalances between vasoconstrictive and vasodilatory factors, probably accompanying implantation and placentation. The use of aspirin to prevent the development of hypertension and preeclampsia is currently being studied because it has been shown to shift the balance toward the metabolism of the vasodilatory prostaglandin, prostacycline. At this time, aspirin is only advised for women at high risk for developing preeclampsia. Calcium may also be a preventative mineral, and a diet that is adequate during pregnancy is advised.