Cervical pessary versus progesterone for preterm birth prevention in twin pregnancy with short cervix

BACKGROUND: Both twin pregnancy and short cervix are risk indicators for preterm birth. Cervical pessary and progesterone have been suggested to prevent preterm birth. A randomised trial was conducted in individuals carrying twins with cervix below the 25th centile (less than 38 mm). METHODS: We conducted a single centre open-label randomised clinical trial at Monash Medical Centre in Victoria, Australia (Trial registration number: ACTRN12616000875404). Individuals with a twin pregnancy and mid-trimester (16 to 23 weeks) cervical length < 25th percentile were invited to participate. After informed consent, participants were randomly assigned to placement of cervical pessary or self-administered daily vaginal progesterone (200 mg), until 36 weeks of gestation or until onset of labour, whichever occurred first. Primary outcome was a composite adverse neonatal outcome, with preterm birth before 28 weeks as an important secondary outcome. RESULTS: Between 2 December 2019 and 27 July 2023, 159 individuals were screened, of whom 66 had a cervical length ≤ 38 mm, and 34 were randomised to Arabin pessary (N = 16) or progesterone (N = 18). One woman in the progesterone group withdrew consent after randomisation. The study was halted as studies elsewhere had indicated no benefit from pessary. Composite adverse neonatal outcome occurred in 41% (13/32) of the neonates in the Arabin pessary group compared with 29% (10/34) of the neonates in the progesterone group (risk ratio [RR] 1.38, 95% CI 0.71-2.69). Delivery before 28 weeks occurred in 19% (3/16) and 5.9% (1/17) (RR: 3.19, 95% CI 0.37-27.58). CONCLUSION: In individuals with a twin pregnancy and a short cervix, we could not report benefit from cervical pessary over progesterone.