Shorter delivery time after labor induction with misoprostol

Introduction: Increasing evidence has demonstrated that intravaginal misopr ostol (PGE1) is more effective in labor induction than dinoprostone (PGE2). Several studies have demonstrated that the administration of PGE1 instead of PGE2 reduces the induction-to-delivery interval. However, it has not bee n fully investigated on which phase of birth the activity of PGE1 is strong er than that of PGE2. We undertook this study to investigate whether the ac tivity of the two prostaglandins are different over time during the inducti on-to-delivery interval. Material and Methods: 155 patients undergoing induction of labor with 50 mu g intravaginal PGE1 were compared with 174 patients treated with 3 mg PGE2. In both groups the procedure was repeated 6, and 24 hours after the first dose until labor was achieved. Induction-to-initiation of labor time, durat ion of labor stages, induction-to-delivery time, mode of delivery, maternal and neonatal morbidity and changes in Bishop score were compared. Results: Demographic characteristics, indications for induction, mode of de livery, fetal weight, maternal and neonatal morbidity and duration of the l abor stages were similar between the groups. A significant difference was f ound in terms of: induction-to-initiation of labor interval (7.37 h [1 - 68 ] vs. 11.25 h [1 - 74], p < 0.01) and induction-to-delivery interval (11.5 h [2.5 - 89] vs. 14.4 h [2.7 - 94], p < 0.05). The Bishop score at the time of the second administration was significantly different from that at admi ssion in the PGE1 group compared to the PGE2 group [PGE1: 4.8 +/- 2/5.6 +/- 1.9, p < 0.0005; PGE2: 3.9 +/- 2/4.2 +/- 1.4, p = 0.09]. This effect of PG E1 remained significant after correction for various explanatory variables. Conclusions: The stronger effect of PGE1 is the consequence of a faster cer vical ripening, which in turn leads to a quicker achievement of active labo r. Discussion: Intravaginal PGE1 compared to PGE2 reduces significantly the in duction-to-delivery time.