The ancillary study is a prospective cohort study of 355 African-American and 315 white-American females from the NHLBl Growth and Health Study as these women progress from age 18-19 years to age 21-22 years. The study includes yearly measurement of anthropometrics, blood pressure, and echocardiographic determination of cardiac output and total peripheral resistance. In addition, factors which may relate to changes in cardiac output and total peripheral resistance, such as circulating blood volume (left ventricular end-diastolic volume), heart rate, left ventricular contractility, whole blood viscosity, and left ventricular mass and geometry are measured.