Cruz-Melguizo S, et al. - In this multicenter, open-label, randomized, noninferiority trial, researchers investigated how a cervical pessary differs from vaginal progesterone when used as a preventive against spontaneous preterm births in pregnant women with cervical lengths 25 mm or less. According to findings, compared with vaginal progesterone, a cervical pessary was not noninferior for preventing spontaneous birth before 34 weeks of gestation in pregnant women with short cervixes.

Methods

• Participants included women with singleton pregnancies and a short cervix (25 mm or less) measured by transvaginal ultrasonography at the second-trimester ultrasonogram.
• Via computer-randomization (1:1), these subjects were randomized into cervical pessary placement or treatment with vaginal progesterone (200 mg/24 hours).
• Researchers focused on spontaneous preterm delivery before 34 weeks of gestation (primary outcome).
• The noninferiority margin was set at 4% with a 0.025 one-sided α level and a statistical power of 80%; that is, if the 95% CI upper bound exceeded 4%, the pessary could not be deemed noninferior.
• To demonstrate noninferiority of the pessary to progesterone, they needed a sample size of 254 women.

Results

• Twenty-seven Spanish hospitals participated in this trial conducted from August 2012 to April 2016.
• There were 254 enrolled subjects, and the intention-to-treat analysis included 246 subjects.
• A similarity in demographic and baseline characteristics was observed across groups.
• The estimated rate of spontaneous delivery before 34 weeks of gestation in the pessary group and in the progesterone group was 14% (n=18/127) and 14% (n=17/119), respectively, with a risk difference of -0.11% (95% CI -8.85% to 8.62%; P=.99).
• The pessary group had a significantly higher incidence of increased vaginal discharge (87% vs 71%, P=.002) and discomfort (27% vs 3%, P<.001).