Pre-induction cervical ripening with 25 microg and 50 microg vaginal misoprostol in 181 nulliparous parturients

To evaluate the effect of intravaginally misoprostol at start dosages of 25 microg and 50 microg when used for pre-induction cervical ripening among nulliparous parturients.

Our observational study involves all cases of partus induction consecutively registered in a Norwegian hospital between September 2002 and August 2006, with the following inclusion criteria: nulliparous, singleton pregnancies >or=37 weeks, an unfavourable cervix (Bishop score 2499 g, received misoprostol vaginally every 6 h upto four times. Seventy-six women started with 25 microg (25 microg-group) and 105 started with 50 microg (50 microg-group). All continued with 25 microg. Primary outcome was vaginal delivery within 48 h after the first misoprostol dose. Secondary outcome was caesarean section performed within 96.

Vaginal delivery within 48 h after the initial dose occurred more often in the 25 microg-group than in the 50 microg-group (75 vs. 58%, p = 0.018). The rate of caesarean section was lower in the 25 microg-group than in the 50 microg-group (19 vs. 33%, p = 0.043). These differences remained significant after adjusting for confounders.

Our findings support the notion that the dose of 25 microg misoprostol is as at least as efficient as 50 microg in nulliparous parturients.