The prospects for vaginal delivery in gestations beyond 43 weeks.

Abstract

To reveal factors influencing the prospect for vaginal delivery in very prolonged pregnancy. Thirty-six nulliparae and 14 multiparae delivered beyond 43 weeks followed a routine surveillance protocol. Labor was induced on strict indications (n = 11; oligohydramnios, large fetus, hypertension) and on "soft' indications (n = 24; favorable cervix, emotional stress). Receiver operating characteristic curves were obtained for maternal stature and birthweight with regard to mode of delivery. Student's unpaired t-test, Mann-Whitney U test, and Fisher's exact test were used with a two-tailed p < 0.05 considered statistically significant. Labor started spontaneously within three days in > 50% of cases managed expectantly. All multiparae had nonoperative vaginal deliveries. Of nulliparae, 89% delivered vaginally if spontaneous labor and 56% if induced. Failure to progress was the most common reason for operative delivery. A maternal height of < or = 160 cm, a very unripe cervix, and a birthweight > 4250 g were unfavorable factors in induced nulliparae. No case of perinatal mortality, severe birth asphyxia, meconium aspiration, or shoulder dystocia occurred. Fetal meconium release, fetal distress in labor, and birth asphyxia did not significantly differ with regard to parity or mode of labor. The prospect for vaginal delivery was strongly associated with parity. All multiparae had nonoperative vaginal deliveries, irrespective of spontaneous or induced labor. In nulliparae, a spontaneous onset was favorable but a maternal height of < or = 160 cm, a very unripe cervix, and a birthweight > 4250 g were unfavorable factors. In uncomplicated pregnancy with favorable factors spontaneous labor can be awaited for a few days.