Prospective observational study on response to induction of labor with vaginal misoprostol 200 μg and its determinants in routine clinical practice: a multicenter study

Objective: Field-practice’ studies on vaginal misoprostol 200 μg are scant, and only few data exist on the predictive factors for labor success with this molecule. Moreover, there are no published data on the use of vaginal misoprostol specifically referring to the Italian scenario, due to its recent introduction into the market. Here, we report the results of an Italian multicenter prospective observational study on prognostic factors of response to induction to labor with vaginal misoprostol 200 μg. Study Design: Consecutive women treated with removable vaginal misoprostol 200 μg in nine Italian centers were enrolled. After drug insertion, vaginal examinations were performed at 6, 12, 18 and 24 hours. The modified Bishop score, the time and mode of delivery of the neonate and indication for caesarean delivery or reason for instrumented vaginal delivery were also recorded. Results: A total of 197 women were enrolled. Of them, 117 (58.8%) were nulliparae and 71 (35.8%) had a Bishop score at insertion ≤1. Indication to induction was post-term pregnancy in 87 (43.7%) cases, fetal reasons in 33 (16.6%), maternal reasons in 82 (41.2%) and other in 14 (7.0%) cases. Vaginal birth within 24 hours from the beginning of induction was reported in 100 (50.8%) women (43.25 among nulliparae and 81.4 among parae). The median time from misoprostol insertion to vaginal delivery for women of any parity was 17.5 hours: the corresponding values in nulliparae and parae 20.0 and 13.1 hours, respectively. The caesarean delivery rate was 21.8% (43 cases). Reasons for caesarean delivery in women treated with the 200-μg misoprostol were: pathologic fetal health rate pattern in 23 patients (53.5%), lack of efficacy in eight (18.6%), prolonged labor in eight subjects (18.6%), maternal request in three (7.0%), and maternal hypertension in one (2.3%). Parity was associated successful induction (RR vs nullipara: 4.26). There were no fetal, maternal or neonatal deaths. Tachysystole requiring intervention occurred in 58 cases (29.4%). Conclusions: Misoprostol 200 μg VDR is an effective and safe approach to induction of labor, regardless of several factors including Bishop’ score, age and maternal BMI.