Double-blind comparison of 2.5 and 5.0 mg of prostaglandin E2 gel for preinduction cervical ripening

OBJECTIVE: To compare the effectiveness and safety of 2.5 vs. 5.0 mg of prostaglandin E2 (PGE2) gel for preinduction cervical ripening. STUDY DESIGN: Patients presenting for induction of labor with an unfavorable Bishop score (≤4) were assigned randomly, in a double-blind manner, to receive either 2.5 or 5.0 mg of PGE2 gel intravaginally. A repeat Bishop score was determined in four to six hours, and if the score was still unfavorable, the same dose of gel was administered a second time. All patients returned within 12 hours for induction of labor. RESULTS: A total of 119 patients received PGE2 gel, 55 in the 2.5-mg group and 64 in the 5.0-mg group. Both groups were similar with respect to age, parity, race, indication for induction and preinduction Bishop score. Both doses of PGE2 gel were safe and effective. The need for additional doses of gel, the need for and duration of oxytocin use, and the duration of labor were similar in both groups. More infants whose mothers received the 5.0-mg dose had one-minute Apgar scores < 7 (P = .027). No significant difference in five-minute Apgar scores was noted. Cesarean delivery for failed induction was uncommon, occurring in 3.6% of patients who received 2.5 mg and in 4.7% of patients who received 5.0 mg of PGE2 gel (P = NS). Finally, the incidence of hyperstimulation was 3.6% in the 2.5-mg group and 1.6% in the 5.0-mg group (P = NS). Conclusion: A 5-mg dose of PGE2 gel was neither more effective nor associated with more side effects than the more commonly used 2.5-mg dose.