Background: Women with twin pregnancies and a dilated cervix in the second trimester are at increased risk of pregnancy loss and early preterm birth; there is currently no proven therapy to prevent preterm birth in this group of women.
Objective: This study aimed to determine whether physical examination-indicated cerclage reduces the incidence of preterm birth in women with a diagnosis of twin pregnancies and asymptomatic cervical dilation before 24 weeks of gestation.
Study design: Multicenter, parallel group, open-label, randomized controlled trial of women with twin pregnancies and asymptomatic cervical dilation of 1 to 5 cm between 16 weeks 0/7 days of gestation and 23 weeks 6/7 days of gestation were enrolled from July 2015 to July 2019 in 8 centers. Eligible women were randomized in a 1:1 ratio into either cerclage or no cerclage groups. We excluded women with monochorionic-monoamniotic twin pregnancy, selective fetal growth restriction, twin-twin transfusion syndrome, major fetal malformation, known genetic anomaly, placenta previa, signs of labor, or clinical chorioamnionitis. The primary outcome was the incidence of preterm birth at <34 weeks of gestation. Secondary outcomes were preterm births at <32, <28, and <24 weeks of gestation, interval from diagnosis to delivery, and perinatal mortality. Data were analyzed by intention-to-treat methods.
Results: After an interim analysis was performed, the Data and Safety Monitoring Board recommended stopping the trial because of a significant decrease in perinatal mortality in the cerclage group. We randomized 34 women, with 4 women being excluded because of expired informed consent. A total of 17 women were randomized to physical examination-indicated cerclage and 13 women to no cerclage. Whereas 4 women randomized to cerclage did not receive the surgical procedure, no women in the no cerclage group received cerclage. Maternal demographics were not significantly different. All women in the cerclage group also received indomethacin and antibiotics. When comparing the cerclage group vs the no cerclage group, the incidence of preterm birth was significantly decreased as follows: preterm birth at <34 weeks of gestation, 12 of 17 women (70%) vs 13 of 13 women (100%) (risk ratio, 0.71; 95% confidence interval, 0.52-0.96); preterm birth at <32 weeks of gestation, 11 of 17 women (64.7%) vs 13 of 13 women (100%) (risk ratio, 0.65; 95% confidence interval, 0.46-0.92); preterm birth at <28 weeks of gestation, 7 of 17 women (41%) vs 11 of 13 women (84%) (risk ratio, 0.49; 95% confidence interval, 0.26-0.89); and preterm birth at <24 weeks of gestation, 5 of 17 women (30%) vs 11 of 13 women (84%) (risk ratio, 0.35; 95% confidence interval, 0.16-0.75). The mean gestational age at delivery was 29.05±1.7 vs 22.5±3.9 weeks (P<.01), respectively; the mean interval from diagnosis of cervical dilation to delivery was 8.3±5.8 vs 2.9±3.0 weeks (P=.02), respectively. Perinatal mortality was also significantly reduced in the cerclage group compared with the no cerclage group as follows: 6 of 34 women (17.6%) vs 20 of 26 women (77%) (risk ratio, 0.22; 95% confidence interval, 0.1-0.5), respectively.
Conclusion: In women with twin pregnancies and asymptomatic cervical dilation before 24 weeks of gestation, a combination of physical examination-indicated cerclage, indomethacin, and antibiotics significantly decreased preterm birth at all evaluated gestational ages. Most importantly, cerclage in this population was associated with a 50% decrease in early preterm birth at <28 weeks of gestation and with a 78% decrease in perinatal mortality.
Trial registration: ClinicalTrials.gov NCT02490384.
Keywords: cerclage; cervical dilation; perinatal mortality; physical examination–indicated cerclage; preterm birth; twins.
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