Blood pressure regulation in third-trimester pregnant women receiving tocolytic terbutaline infusion

Abstract

Terbutaline (20 μg/min) was infused during 30 min in 17 women in whom a manual external manipulation of a breech presentation was going to be attempted. A significant increase in systolic ( P = 0.003) and a decrease in diastolic blood pressure ( P = 0.04) was noted at the end of the infusion but no change in mean arterial blood pressure was obtained. At the same time aldosterone serum levels had dropped significantly ( P = 0.009) and plasma angiotensin II showed a marked increase ( P < 0.001) which continued during the next 30 min. All changes were normalized after the infusion. The angiotensin-converting enzyme activity remained unchanged, as did vasopressin plasma levels. The combined results of terbutaline provocation have been interpreted to mean that blood pressure regulation in third-trimester pregnant women is similar to that in nonpregnant individuals. The increase in dehydroepiandrosterone sulphate ( P < 0.05) noted at the end of infusion was suggested to be related to the blood pressure changes and was unrelated to fluctuations in serum cortisol. The latter steroid increased between 30 and 60 min, e.g. during the manual external manipulation, and was interpreted as being due to maternal stress.