Serial hemodynamic investigations were performed in 40 women at 38 weeks' gestation and then 1, 2, 6, 10, and 14 days after normal delivery. Cardiac output was measured by Doppler and cross-sectional echocardiography at the aortic valve. In 30 controls who received an average of 280 mL intravenous fluid during labor, the mean cardiac output remained elevated (7.15 L/minute) for 24 hours after delivery and then fell to 5.39 L/minute at 10 days as a result of decreases in both heart rate and stroke volume. Blood pressure fell during the first 2 days after delivery and thereafter increased to values not significantly different from those recorded at the end of pregnancy. In ten women who experienced postpartum hemorrhage, stroke volume decreased and heart rate increased, relative to the control group, during the first 48 hours after delivery. Blood pressure and cardiac output, however, were not significantly different from values in the control group.