Heart-rate changes after transition from a supine to a standing posture were measured in 12 hypertensive and 12 normotensive primigravid women, in their last trimester of gestation. The subjects beat-to-beat heart-rate (HR) changes were recorded on both an ordinary cardiotocograph and on magnetic tape. The hypertensive patient group (1) reached an HR-maximum after standing up in a significantly shorter period of time and (2) had a significantly lower HR during 1 min erect posture. A population threatened by pregnancy-induced hypertension might be detected by using the non-invasive method of recording the maternal beat-to-beat heart-rate changes after transition to the standing posture, even before the onset of hypertension