For a study, researchers sought to determine if a synthetic osmotic cervical dilator was as effective as oral misoprostol for cervical ripening. Pregnant women having induction of labor at 37 weeks or more with Bishop scores less than six were randomly assigned to mechanical cervical dilatation or oral misoprostol in an open-label, noninferiority randomized study. Mechanical dilation participants had synthetic osmotic cervical dilator rods inserted, whereas misoprostol participants had up to six doses of 25 micrograms orally every 2 hours. After 12 hours of ripening, oxytocin was released by artificial membrane breach. The physician was in charge of labor management. The main outcome was the proportion of women who delivered vaginally within 36 hours of starting the research intervention. Increased Bishop score, delivery method, induction-to-delivery interval, the overall length of hospital stay, and patient satisfaction were all secondary outcomes. A sample size of 306 individuals was required based on a noninferiority margin of 10%, an estimated primary outcome frequency of 65% for misoprostol and 71% for mechanical techniques, and an 85% power.

About 307 women were randomized from November 2018 to January 2021, including 151 evaluable participants in the synthetic osmotic cervical dilator group and 152 in the misoprostol group (four early withdrawals). Mechanical cervical dilatation resulted in a larger proportion of women achieving vaginal birth within 36 hours than misoprostol (61.6% vs. 59.2%), with an absolute difference of 2.4% (95% CI 9% to 13%), demonstrating noninferiority for the prespecified margin. There were no variations in the way of delivery. Misoprostol caused greater tachysystole (70 [46.4%] versus 35 [23.3%]; P=.01). The synthetic osmotic cervical dilator group had better sleep, fewer unpleasant gut feelings, and lower pain levels (P<.05).

For cervical ripening, a synthetic osmotic cervical dilator was not inferior to oral misoprostol. The benefits of a synthetic osmotic cervical dilator included a superior safety profile and patient satisfaction, less tachysystole, lower pain scores, and FDA clearance.