[Uterine activity in primiparous and multiparous women in spontaneous labor and induced labor with oxytocin].

Abstract

An analysis was performed of 5187 intra-amniotically measured labor pressure curves in 40 births with spontaneous labour (20 primiparae and 20 multiparae) and 40 births births in which labor was induced with oxytocin (20 primiparae and 20 multiparae). The dilatation of the os uteri was divided into three phases--Phase 1, dilatation of the cervix to 2 cm; Phase 2, dilatation of the cervix from 2 to 4 cm, and Phase 3, dilatation from 4 cm onwards until complete. During the active phase, from 2 cm until dilatation of the os uteri was complete, no differences were observed between induced and spontaneous labor with regard to frequency and amplitude of contractions. In the induced-labor cases, the parameters for uterine activity, maximum contraction and dilatation speed were higher in all three phases of labor, and those for total duration of labor lower than in the spontaneous labor cases. The contraction/dilatation speed is an important parameter for monitoring the effect of drug-induced stimulation of labor. In the latency phase in spontaneous labor, more contractions were observed in multiparae than in primiparae. This fact which should be reason enough to intensify monitoring of both mother and fetus during this phase. In light of these results it would appear advisable, in the absence of progress in labor, to make a clear distinction between the goals of cervical maturity and promotion of uterine activity, and to institute different drug therapy accordingly.