Cervical ripening before medical induction of labor: a comparison of prostaglandin E2, estradiol, and oxytocin.

Objective: Our purpose was to evaluate the effectiveness of oxytocin, prostaglandin E2 intracervical gel, and estradiol cream for ripening the very unfavorable cervix in patients requiring induction of labor at term.

Study Design: This prospective, randomized study was conducted in a population of women with a very unfavorable cervix (Bishop score < 4) requiring induction of labor. The patients received prostaglandin E2 gel (0.5 mg) intracervically (three doses 6 hours apart), 4 mg estradiol cream in the anterior fornix of the vagina (three doses 6 hours apart), or oxytocin at induction per protocol with an infusion pump.

Results: Ninety-nine women were recruited into this trial and evenly distributed among the three groups. The demographics of maternal age, race, parity, gestational age, initial Bishop score, and indication for induction were similar among the groups. The incidence of cesarean deliveries was similar in the three groups with approximately 59% of pregnancies delivered abdominally. For patients undergoing abdominal delivery the maximum cervical dilatation among the oxytocin, estradiol, and prostaglandin E2 groups was similar (3.90 +/- 3.02 cm, 3.63 +/- 2.79 cm, and 4.65 +/- 2.78 cm, respectively; p > 0.05). For all patients birth weight and Apgar scores at 1 and 5 minutes were comparable across all regimens (p > 0.05). In the subset of patients delivered vaginally patients receiving oxytocin for cervical ripening had the greatest improvement in Bishop score over baseline (p = 0.023) with an improvement of 7.08 +/- 2.42.

Conclusion: No differences were detected among prostaglandin E2 gel, estrogen, and oxytocin in relation to cervical ripening in patients with an unfavorable cervix at term who require an induction of labor. Patients with a very unfavorable cervix at term who require delivery may benefit from serial ripening and inductions.