Characteristics of the included studies.

Objective
To compare the therapeutic effects of emergency cervical cerclage and expectant treatment in preterm birth due to cervical insufficiency in singleton pregnancy.
Methods
A combination of subject words and free words was used to search major domestic and foreign databases. According to inclusion and exclusion criteria, 23 studies were included that met the criteria and quality evaluation and data extraction was carried out. The data were analyzed using STATA 15 and the reporting was done in reference to the list of Preferred Reporting Items for Systematic and Meta-Analyses.
Results
Emergency cervical cerclage was superior to expectant treatment for the primary outcome of pregnancy prolongation (WMD = 5.752, 95% CI 5.194–6.311, 22 studies, N = 1435, I2 = 97.1%, P = 0.000). Cervical cerclage was also superior to expectant treatment for the secondary outcomes of neonatal birth weight (WMD = 1051.542, 95% CI 594.107–1508.977, 9 studies, N = 609, I2 = 96.4%, P = 0.000), neonatal Apgar 1′ (WMD = 2.8720, 95% CI: 2.105–3.639, 11 studies, N = 716, I2 = 99.0%, P = 0.000), number of live births (OR = 6.018, 95% CI 2.882–12.568, 10 studies, N = 724, I2 = 55.3%, P = 0.000), deliveries after 32 weeks (OR = 8.030, 95% CI 1.38–46.892, 8 studies, N = 381, I2 = 85.9%, P = 0.021). deliveries after 34 weeks (OR = 15.91, 95% CI 5.92–42.77, 9 studies, N = 560, I2 = 59.6%, P = 0.000), number of vaginal deliveries (OR = 3.24, 95% CI 1.32–7.90, 8 studies, N = 502, I2 = 69.4%, P = 0.018), and number of neonatal survivals (OR = 9.300, 95% CI 3.472–24.910, 10 studies, N = 654, I2 = 80.5%, P = 0.000). No difference between emergency cervical cerclage and expectant treatment was found in patients with chorioamnionitis (OR = 1.85, 95% CI 0.602–4.583, 4 studies, N = 296, I2 = 16.3%, P = 0.273).
Conclusion
Before the 28th week of pregnancy, emergency cervical cerclage can significantly prolong the gestational week and improve the neonatal survival rate, compared to expectant treatment, in women with singleton pregnancies who have a dilated uterine orifice caused by cervical insufficiency.