Serial measurements of apparent liver blood flow and cardiac output were performed in 12 women at 12-14, 24-26 and 36-38 weeks of pregnancy and then at 10-12 weeks after delivery. Apparent liver blood flow was calculated from indocyanine green clearance. Cardiac output was measured by Doppler and cross-sectional echocardiography at the aortic valve. Postnatal apparent liver blood flow was 1.81 l/min and no significant change was demonstrated during pregnancy. In contrast cardiac output decreased from 7.46 l/min at 36-38 weeks gestation to 4.90 l/min after delivery. Apparent liver blood flow accounted for 24% of cardiac output during pregnancy. This increased to 37% after delivery.