Quantitative analysis in the oxytocin challenge test.

A quantitative analysis of the oxytocin challenge test (OCT) was carried out in 305 women to evaluate: (1) the intrauterine pressures evoked during the oxytocin infusion, (2) when fetal heart rate (FHR) decelerations are likely to occur, (3) the type and amount of decelerations which are significant, and (4) what clinical events and laboratory parameters correlate with the OCT. If contractions are evoked at a rate of three per 10 minutes, the pressure profile mimics normal labor. The first FHR deceleration is likely to occur between the second and third effective contraction. A deceleration/contraction ratio greater than or equal to 10% significantly forecasts an abnormal FHR during parturition and an increased chance of a cesarean section.