OC20.03: *Cervical pessary versus vaginal progesterone in multiples with a short cervix: a randomised controlled trial

Multiple pregnancy and a mid-gestation short cervix are known risk factors for spontaneous preterm birth (sPTB). We aimed to compare the effectiveness of cervical pessary and vaginal progesterone in multiples without a previous sPTB < 34 weeks of gestation and with a short cervix for the improvement of perinatal outcome through prevention of PTB. We performed an open-label multi-centre randomised clinical trial in 20 hospitals in the Netherlands (EUCTR2013-002884-24-NL). Asymptomatic individuals with a multiple (twin or triplet) pregnancy without previous sPTB < 34 weeks and with a mid-gestation cervical length < 38mm were randomised in a 1:1 ratio to receive either an Arabin cervical pessary or vaginal progesterone 200mg daily. Primary outcome was a composite of adverse perinatal outcomes. Secondary outcomes were rates of (s)PTB < 24, 28, 32, 34 and 37 weeks. Treatment effect was expressed as relative risk (RR) and 95% confidence intervals (CI). The sample size was set at 332 women and analysis was by intention-to-treat. The study was halted for futility based on the results of 237 participants at the 4th interim analyses. Between October 2014 and August 2023, we randomised 277 multiples, including 7 triplets, (pessary N = 138, progesterone N = 139) with 531 neonates (pessary N = 267, progesterone N = 264). The composite adverse perinatal outcome occurred in 19.5% of neonates in the pessary group versus 13.3% of neonates in the progesterone group (crude RR 1.6; 95% CI 0.99 – 2.5). The rates of (s)PTB were not significantly different between groups. In the predefined subgroup of cervical length ≤ 25mm, the composite perinatal outcome was equally frequent in the pessary and progesterone group (43.6% vs 34.0%, RR 1.5; 95% CI 0.68 – 3.3). In multiples without a history of previous sPTB < 34 weeks and with a mid-gestation cervical length < 38mm or ≤ 25mm, treatment with a pessary or progesterone did not result in statistically significant differences in the prevention of a composite adverse perinatal outcomes.