Prevention of preterm birth with pessary in singletons (PoPPS): randomized controlled trial

Objective To determine if pessary use prevents preterm birth (PTB) in women with singleton pregnancy, with short cervical length (CL) measured on transvaginal sonography (TVS) and without prior spontaneous PTB (sPTB). Methods This was an open-label multicenter randomized trial of asymptomatic women presenting at 18 + 0 to 23 + 6weeks' gestation with a singleton pregnancy, CL <= 25mm on TVS and no prior sPTB. sPTB included those with spontaneous onset of labor and those with rupture of membranes prior to labor. Subjects were randomized to receive either a Bioteque cup pessary or no pessary. Pessaries were inserted by trained maternal-fetal medicine staff. Vaginal progesterone was recommended to women with CL <= 20 mm. The primary outcome was PTB < 37 weeks. A sample size of 121 women in each group (n = 242) was needed to detect a reduction in the primary outcome from 30% in the no-pessary group to 15% in the pessary group. The trial was stopped early before complete enrollment. Results Between 17 March 2014 and 29 July 2016, 17 383 women underwent CL measurement on TVS. Of these, 422 (2.4%) had CL <= 25mm and 391 (92.7%) met the full eligibility criteria, of which 122 (31.2%) agreed to randomization. Sixty-one (50%) women were randomized to the pessary group and 61 (50%) to the no-pessary group. Baseline characteristics were similar between the groups. There were no significant differences between the pessary and no-pessary groups in the rate of PTB < 37 weeks (43% vs 40%; relative risk 1.09; 95% CI, 0.71-1.68) or in secondary outcomes, such as rate of PTB < 34 weeks, rate of PTB < 28 weeks, gestational age at delivery, birth weight and rate of composite adverse neonatal outcome. Conclusions Cervical pessary use was not associated with prevention of PTB in women with a singleton pregnancy, short CL on TVS and no prior sPTB in this small, underpowered randomized controlled trial. Copyright (C) 2017 ISUOG. Published by John Wiley & Sons Ltd.