Cervical pessary for preventing preterm birth in singletons and twin pregnancies: an update systematic review and meta-analysis

To evaluate the effectiveness of cervical pessary in preventing preterm birth (PTB) and improving perinatal outcomes among singleton and twin pregnancies. Electronic databases were systematically searched from their inception until 14 March 2019. Randomized clinical trials comparing the effectiveness of cervical pessary placement with expectant management were included. The primary outcome was the incidence of PTB <34 weeks. Thirteen studies were included, involving eight studies about singleton and six studies about twin pregnancies. For singleton pregnancies with short cervical length, cervical pessary, comparing with expectant treatment, seemed have no effectiveness in preventing PTB <34 weeks (relative risk, 95% confidence interval, 0.73, 0.42–1.28), <37 weeks (0.69, 0.43–1.09), and <28 weeks (0.79, 0.42–1.48); while for twin pregnancies with short cervical length, cervical pessary also did not reduce the risk of PTB <34 weeks (0.81, 0.49–1.35), <37 weeks (0.93, 0.83–1.05), and <28 weeks (0.72, 0.38–1.38). However, cervical pessary seemed have the effectiveness of reducing the risk of spontaneous PTB <28 weeks (0.50, 0.25–0.99) and low birth weight (<1500 g) (0.68, 0.50–0.94) among twin pregnancies with short cervical length. In addition, cervical pessary increased the rate of vaginal discharge and did not improve perinatal outcomes among both singleton and twin pregnancies. Comparing with the expectant treatment, the effectiveness of cervical pessary for reducing the risk of PTB remains uncertain. Additional trials are warranted to further evaluate the effectiveness of cervical pessary.