Cardiovascular effects of oxytocin

Oxytocin, 5 to 10 units, is frequently given as a bolus injection following term delivery or elective termination of pregnancy. It is not general knowledge that this has any untoward effects. In the present study in young, healthy women undergoing elective termination of pregnancy, mean arterial blood pressure decreased approximately 30% and the total peripheral resistence 50%, 40 seconds after injection. However, heart rate increased 30% and stroke volume 25%, so that the cardiac output was elevated more than 50% above control. Oxytocin given as a dilute solution produced no circulatory change; hence, we suggest that this drug be administered in such fashion rather than by bolus injection.