The alterations in the systolic time intervals caused by hypertension during pregnancy have been investigated. A group of 20 women who developed hypertension only during pregnancy (HP), and a group of 16 women who began pregnancy with established hypertension (EHP) were matched with 25 normal pregnant women (N). the study was performed (1) during the third trimester, (2) five days after delivery and (3) five weeks after delivery, both in supine and in lateral postures. In the third trimester the two hypertensive groups, when compared with the normal group, were characterized by a shorter left ventricular ejection time (LVETi: 407 +/- 3 ms for the normal group v. 390 +/- 2 ms for the HPO group, P less than 0.001; v. 398 +/- 2 ms for the EHP group, P less than 0.02), and a longer pre-ejection period (PEPi: 138 +/- 2 ms for the normal group v. 154 +/- 2 ms for the HP group P less than 0.001; v. 145 +/- 1 ms for the EHP group, P less than 0.05). When the two hypertensive groups were compared with each other the HP group showed a shortened LVET and a prolonged PEP (P less than 0.01), and also a slower heart rate (HP 74 +/- 3 b min-1. EHP 83 +/- 3 b min-1 P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)