During pregnancy and the post partum period important cardiovascular adjustments take place, which for ethical views need a non invasive approach. In the present work we studied the alterations of the Systolic Time Intervals in both supine and lateral decubitus during each trimester and at the fifth day and fifth week after delivery. In the first part of pregnancy a significant reduction of the preejection time (PE) and PE/EVS with an increase of the left ventricular ejection time (EVS) become evident. In the second part the picture reverses to a significantly reduced EVS and increased PE and PE/EVS. This picture even if decreasing, is present in the post partum period. The first part of pregnancy is characterized by a hyperkinetic condition; in the second one the position of the woman becomes important, and the reduction of the EVS is at least partially due to an impaired venous return (compression of the vena cava by the gravid uterus). The persistence of altered systolic time intervals in the post partum (increased PE/EVS) suggest an impaired myocardial performance.