Maternal circulatory response to a single dose of ritodrine hydrochloride during orthostasis in normal and hypertensive late pregnancy.

Placental blood perfusion, the maternal heart rate, and arterial blood pressure were measured before and after a single intramuscular dose of ritodrine hydrochloride during orthostasis in 11 healthy pregnant women, 10 pre-eclamptic patients, and 11 pregnant patients with essentially hypertension. There was a slight increase in placental blood perfusion in the healthy subjects and a significant rise in the pre-eclamptic patients and the women with essential hypertension. The heart rate increased significantly in all groups. No greater changes in the systolic and diastolic blood pressures were observed. The clinical significant of the results is discussed briefly.