Randomization of two dosing regimens of vaginal misoprostol for cervical ripening and labor induction in a low...

To compare the effectiveness of two dosing regimens of vaginal misoprostol for cervical ripening and induction of labour.

Pregnant women with singleton low risk pregnancy at term scheduled for elective induction of labour were randomized to receive either 25 μg or 50 μg of vaginal misoprostol for pre-labour cervical ripening. All the patients received antenatal care and delivered at the University College Hospital (UCH) from January 1 st to May 31 st 2006. A total of 128 patients were randomized; 65 patients received 25 μg and 63 patients received 50 μg of vaginal misoprostol.

Significantly higher number of patients in the 50 μg group progressed to active labour as compared with the 25 μg group (95.2% versus 84.6%, P < 0.05). The need for oxytocin augmentation of labour was higher among the 25 μg as compared with 50 μg (39.7% versus 16.4%, P = 0.007). There was higher proportion of patients in the 50 μg group delivering vaginally within 24 hours as compared with the 25 μg group (98.2% versus 90.0%, P = 0.063). However, the mean interval between the first dose of misoprostol and vaginal delivery was not statistically different in the two groups (754 ± 362 minutes and 885 ± 582 minutes, P = 0.152). The incidence of caesarean section was similar in the two groups (7.7% versus 11%, P = 0.580). Labour complications, such as precipitate labour, tachysystole and abnormal fetal heart rate patterns were greater in the 50 μg group.

Twenty-five microgram of misoprostol appears to be as effective as 50 μg for pre-induction cervical ripening and labour induction. Though 50 μg of vaginal misoprostol resulted in relatively faster delivery and less need for oxytocin augmentation, it was associated with more labour complications as compared with 25 μg of misoprostol.