Efficacy of sublingual misoprostol for induction of labor at term and post term according to parity and membrane integrity : a prospective observational study

Objective: To evaluate the effectiveness and safety of 25 mcg sublingual misoprostol for induction of Labor at term according to parity and membrane integrity. Methods: We conducted a prospective observational study on singleton pregnancies undergoing induction of Labor at term. Twenty-five mcg of misoprostol were administered sublingually every 4 h. Main outcomes were vaginal deliveries within 24 h, time-to-vaginal-delivery, hyper-stimulation syndrome, cesarean section rate, arterial pH< 7.0 and NICU admission rate. Results: We studied 508 patients, 375 nulliparous and 133 multiparous women. Sixty-five percent and 78%, respectively, delivered vaginally within 24 h from first administration. Median time-to-vaginal-delivery was significantly shorter in PROM than in women with intact membranes (p < 0.001). Epidural analgesia prolonged time-to-vaginal-delivery among nulliparous women (p < 0.0005). A positive correlation between BMI and time to delivery was observed in both nulliparous and multiparous women (p < 0.05). Cesarean section rate was 22% in nulliparous and 6% in multiparous group. Induction failure was 1.4% and uterine hyper-stimulation 1%. No pH≤ 7.00 was recorded; overall 7 (1.4%) newborns were admitted to NICU. Conclusions: Sublingually administered misoprostol is an effective and safe method for induction of Labor at term. Parity, status of membranes and BMI significantly affect time to delivery.