Two different regimens of preinduction ripening of the uterine cervix with prostaglandin E2: a randomized clinical study

A randomized clinical study was designed to test the relative efficacy of preinduction cervical ripening with 0.25 mg prostaglandin E₂ (PGE₂), repeated if necessary (group 1) compared to a single maturation with 0.50 mg PGE₂ (group 2). In group 1 (n = 42), the ripening process was repeated every day until spontaneous onset of labor occurred or induction with oxytocin was decided (for improved Bishop score above 5, or maternal or fetal distress). In group 2 (n = 42) the patients who had not labored 12 h after the maturation procedure had labor induced with oxytocin, irrespective of their cervical status. In group 1, 28 patients experienced repeated maturations (from 2 to 9). Thirty patients had an induction of labor with oxytocin in group 2 and only 12 in group 1 (P < 0.0001). There were four failures of induction of labor in group 2 and none in group 1 (P < 0.05). Three episodes of myometrial hyperstimulation requiring an emergency cesarean section for acute fetal distress occurred in group 2 and none in group 1. There were 13 cesarean sections in group 2 and eight in group 1. The outcome of pregnancy was otherwise similar in both groups. In order to avoid failure of induction of labor, pre-induction cervical ripening with 0.25 mg PGE₂, repeated daily if necessary, is therefore recommended in high risk pregnancy unless a severe maternal or a fetal distress call for a prompt delivery irrespective of the cervical status.