[Determination of the heart minute volume by impedance cardiography: a way to prophylaxis of premature birth? (author's transl)].

30 gravid women between the ages of 18 and 38 years who had gone into premature labour of unknown etiology were examined with respect to cardiac output and various other cardiovascular parameters in the standing, supine and left lateral positions. Measurements were carried out using an impedance-cardiography. A group of 30 women of similar age and duration of pregnancy but not in premature labour was also tested as controls. In the standing position, the test group showed a cardiac output which was 15% less than that of the controls. Statistically this was highly significant (p less than 0.005). No difference was found in the supine and left lateral positions. These results are in agreement with the literature, but with the method used in this study, an invasive, or X-Ray procedure is avoided. The physiology of the cardiovascular system in pregnancy and the means by which premature labour may be prevented, are discussed.