Real-time microcomputer-based analysis of spontaneous and augmented labor

In an attempt to develop a reproducible, objective measure of adequate uterine activity in labor, real-time measurements of intrauterine pressure amplitude and contraction frequency, interval, duration, and integral were made in 54 patients, 11 of whom received oxytocin augmentation. We determined the active pressure integral required per centimeter of cervical dilatation, expressed in kPa seconds, and the mean active pressure, expressed in kPa. The augmented group had a significantly higher mean active pressure integral per centimeter than those in normal labor (P < .01). There was a trend, which did not reach statistical significance, for subjects who required oxytocin augmentation of labor to develop a higher mean active pressure than those in normal labor. However, the correlation of any uterine contractility index (Montevideo units, Alexandria units, mean active pressure) with progress in labor was poor. We conclude that women with dysfunctional labor require more uterine activity for progress in labor than women with normally progressing labor, and that the computer-derived 'area under the curve' is not a better predictor of labor progress than Montevideo units.