Cervical pessary for preventing preterm birth in twin pregnancies with maternal short cervix after an episode of threatened preterm labor: randomised controlled trial.

Background: No intervention has proved effective to date in reducing the spontaneous preterm birth rate in twin pregnancies following an episode of threatened preterm labor and with a short cervix remaining. This study was designed to ascertain whether cervical pessaries are useful in preventing spontaneous preterm birth in women with twin pregnancies and a short cervix remaining after a threatened preterm labor episode.

Study Design: This open, randomized, controlled trial was conducted in 132 pregnant women who had not delivered 48 hours after a threatened preterm labor episode and had a short cervix remaining (≤20 mm between 24 and 29 weeks and ≤10 mm between 30 and 33 weeks). Patients were randomly assigned to cervical pessary (n = 67) or routine management (n = 65). The primary outcome was the spontaneous preterm birth rate before 34 weeks. Spontaneous preterm birth before 28 and 37 weeks and neonatal morbidity and mortality were also evaluated in an intention-to-treat analysis.

Results: Significant differences were observed in the spontaneous preterm birth rate before 34 weeks between the pessary and routine management groups (11 of 67 [16.4%] in the pessary group vs 21 of 65 [32.3%] in the control group; relative risk, 0.51 [confidence interval, 0.27-0.97]; P = .03). No significant differences were observed in the preterm birth rate < 28 weeks or < 37 weeks between groups. The pessary group less frequently required readmission for new threatened preterm labor episodes (4 of 67 [5.6%] vs 14 of 65 [21.5%]; relative risk, 0.28 [confidence interval, 0.10-0.80]; P = .009). Significant reduction was observed in the number of neonates weighing less than 2500 g (17.9% [24 of 134] vs 70.8% [92 of 130]; relative risk, 0.25 [confidence interval, 0.15-0.43]; P < .0001).

Conclusion: Pessary use did significantly lower the spontaneous preterm birth rate before 34 weeks in twin pregnancies with maternal short cervix remaining after a threatened preterm labor episode. Pessary use also reduced the threatened preterm labor recurrence and neonates' weight less than 2500 g.