Cervical pessary in singleton gestations with arrested preterm labor: a randomized clinical trial

Background: Cervical pessary been proven to be effective in asymptomatic women with singleton gestations and with short midtrimester cervical length, while efficacy of this device in women with arrested preterm labor is still a subject of debate. Objective: To test the hypothesis that in women with singleton pregnancy, and with arrested preterm labor, use of cervical pessary would reduce the rate of preterm birth at less than 37 weeks of gestation. Methods: Parallel group, non-blinded, randomized trial. Eligible women were those with a diagnosis of arrested preterm labor between 24 0/7 - 33 6/7 weeks of gestations. Participants were randomized in a 1:1 ratio to either cervical pessary or no pessary. The primary endpoint was preterm birth at less than 37 weeks of gestation. A sample size of 120 participants was planned, but the trial was stopped before complete enrollment. Results: 61 women with singleton pregnancies and arrested preterm labor at 24 0/7 - 33 6/7 weeks were enrolled in the trial. 32 women were randomized into the cervical pessary group, and 29 into the control group. Preterm birth at less than 37 weeks of gestation occurred in 14 women (43.8%) in the pessary group, and 6 women (20.7%) in the control group (relative risk 2.98, 95% confidence interval 0.96 to 9.30). Conclusions: In this underpowered trial, among women with singleton pregnancies and arrested preterm labor, use of a cervical pessary, compared with no pessary use, does not result in a lower rate of preterm birth at less than 37 weeks of gestation.