This project is a clinical study of women with high blood pressure who become pregnant. Preeclampsia is a syndrome developing at the end of a pregnancy characterized by an abrupt rise in blood pressure (BP), blood clotting and kidney dysfunction, and may result in premature delivery, infant death, and maternal bleeding, kidney failure and stroke. The goal is to determine whether lowering blood pressure to a normal pressure of 120/80 is associated with a lower incidence of preeclampsia. Women who are completely healthy have a 5% chance of developing preeclampsia, however women with preexisting high blood pressure have a 25% chance of this complication. Several studies, including our own suggest that higher blood pressure early in pregnancy (<20 weeks) is associated with an even higher risk of preeclampsia. Currently we, the researchers at Weill Medical College of Cornell University, do not know how to treat women with high blood pressure and/or kidney disease during pregnancy. Keeping the BP in the normal range may be beneficial to the mother. On the other hand, we are not sure if the blood pressure lowering or the medications may or may not have adverse effects for the baby. Different trials to answer this question have been performed with no clear conclusions. Because of these uncertainties, we propose to compare two different strategies for treating women with high BP who become pregnant. We will treat half the women with BP medications to normalize BP (120-130/80 mm Hg) (experimental group) and the other half with the goal of keeping the BP slightly higher (140-150/90-100 mm Hg)(standard therapy group). We will determine which approach results in healthier pregnancies, and lower incidence of preeclampsia. Reducing the incidence of preeclampsia would be of significant benefit to both mothers and babies.