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

Abstract

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 + 6 weeks' gestation with a singleton pregnancy, CL ≤ 25 mm 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 ≤ 25 mm 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 © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Keywords: pessary; preterm birth; randomized controlled trial; short cervix; singleton.