Background: Emergency cervical cerclage (ECC) is of potential value in twin pregnancy, when the cervix is dilated to >1cm. McDonald and Shirodkar were two main techniques of transvaginal cerclage at present. As ECC at extremely high risk of spontaneous preterm birth (sPTB) especially for twins with cervical dilated ≥ 3cm and prolapsed membranes, so which technique has more advantages is still uncertain. Objectives: The aim of our study was to evaluate the effectiveness of ECC performed with combined McDonald-Shirodkar technique in twin pregnancies between 18–26 weeks with painless cervical dilation 1-6cm. Methods: A retrospective, cohort study matched with the degree of cervical dilation was conducted. The study group (case group) included twin pregnancies who underwent combined McDonald-Shirodkar approach with cervical dilation ≥1 cm between 18–26 weeks of gestation at four institutions, from December 2015 to December 2022. To minimize confounding factors, we elucidated the causality structure using a DAG (Figure 1) and performed 1:1 case-control Matching. A control group performed McDonald approach. The primary outcome was gestational age (GA) at delivery. The secondary outcomes were pregnancy latency, the rates of sPTB at <28, <30, <32, <34 weeks, and neonatal outcomes. Additional sub-analysis was performed by dividing the patients into two subgroups of cervical dilation ≥ 3cm and < 3cm. Results: 84 twin pregnancies were managed with either combined McDonald-Shirodkar approach (case group: n=42) or McDonald approach (control group: n=42). Demographic characteristics were not significantly different in two groups(p>0.05). After adjusting for confounders which were represented by a directed acyclic graph (DAG, Figure 1), median GA at delivery was significantly higher (30.5 vs 27 weeks, Bate: 3.40, 95% confidence interval (CI): 2.13-4.67, p<0.001) and median pregnancy latency was significantly longer (56 vs 28 days, Bate: 24.04, 95% CI: 13.31-34.78, p<0.001) in the case group compared with the control group. Rates of sPTB at <28, <30, <32, and <34 weeks were significantly lower in the case group than in the control group. For neonatal outcomes, there were higher birth weight (BW) (1543.75 vs 980g, Bate: 420.08, 95%CI: 192.18-647.98, p<0.001) and significantly lower overall perinatal mortality (7.1% vs 31%, aOR: 0.16, 95% CI: 0.04-0.70, p=0.014) in the case group compared with the control group. And when cervical dilation ≥ 3cm, combined McDonald-Shirodkar procedure can significantly reduce perinatal mortality (8.3% vs 46.7%, aOR:0.09, 95%CI: 0.01-0.77, p=0.028), significantly decrease the risk of delivery at <28, <30weeks, prolong GA at delivery and pregnancy latency compared with McDonald procedure. Conclusions: ECC performed with the combined McDonald-Shirodkar procedure in twin pregnancies with cervical dilation 1-6 cm in mid-trimester pregnancy may reduce the rate of sPTB and improve perinatal and neonatal outcomes compared with McDonald procedure, especially for twins with cervical dilation of 3-6 cm and prolapsed membranes.