Systemic blood pressure, stroke volume, systolic time intervals (measured via impedance cardiography), rheological properties of blood (hematocrit, plasma viscosity and erythrocyte aggregation) and peripheral flow conditions (measured via occlusive impedance plethysmography) were assessed longitudinally in 21 nonpregnant women and in 49 patients from 5th to 41st week of gestation and 4 to 9 days postpartum. Measurements were taken in the left lateral position. The data showed, that dz/dt, stroke volume and cardiac index rose until the 30th week of gestation and decreased throughout the rest of pregnancy. The same changes were observed in the data on diastolic pressure and Heather Index. Peripheral resistance fell during the first trimester and then increased notably throughout the following time of pregnancy. The systolic time intervals become longer in the last trimester of pregnancy, but were characterised by a markedly shortened left ventricular ejection time (LVET). The reduction of stroke volume in the last trimester is due to diminished venous return or venous outflow by obstruction of the inferior vena cava or by abnormalities in the left ventricular function and/or impaired rheological properties of the blood.