**8. Vaginal pessary**

Placement of a ring-shaped plastic around the cervix vaginally has been used to prevent preterm birth for over 50 years, with greater interest being gained since 2003, when it was found that after placement of the pessary in pregnancies there were no preterm births. Thirty-two weeks gestation in a follow-up study of high-risk pregnancies for preterm delivery where a vaginal pessary was placed, delivery before 37 weeks was observed in 50% of women. However, in a randomized study that included singleton pregnancies with a cervical length of 25 mm or less, the rate of preterm delivery in pregnancies who had a pessary inserted was 6%, compared to 27% observed in pregnant women where only follow-up was performed (OR 0.18, 95% CI 0.08, 0.37) [42–46].

In twin pregnancies with a cervical length below the 25th percentile, vaginal pessary use reduced both preterm delivery (before 32 weeks' gestation) and poor perinatal outcome. Specifically, prematurity was 14% in the vaginal pessary group versus 29% in the monitoring group (RR 0.49, 95% CI 0.24, 0.97), while poor perinatal outcome was 2% in the vaginal pessary group versus 29% in the monitoring group (RR 0.4, 95% CI 0.19, 0.83). The results were even more encouraging in the subanalysis of high-risk pregnancies for the occurrence of preterm birth [42–50].
