Abstract: Background　Preterm delivery is a most common serious complication in pregnancy，which occurs at a higher rate in twin pregnancy. Effective prediction and timely delivery of interventions will greatly reduce the preterm delivery rate and improve the neonatal health in twin pregnancy. Objective　To examine the predictive value of transvaginal ultrasound-measured cervix length（CL），and transabdominal ultrasound-measured fetal membrane thickness for preterm delivery in twin pregnancy. Methods　A total of 177 women with twin pregnancy who were treated at the Second Affiliated Hospital of Zhengzhou University from September 2019 to January 2021 were selected. All measured CL by transvaginal ultrasound，fetal membrane thickness and deepest vertical pocket （DVP） by transabdominal ultrasound，received observation of the opening of cervical internal orifice at 20 to 24 weeks gestation，and received observation of uterine malformation assessment based on the results of previous color Doppler ultrasonography，and these 5 indicators were compared by the prevalence of preterm delivery（assessed by the gestational week of delivery in accordance with outpatient follow-up or telephone follow-up result）. The receiver operating characteristic （ROC） curve of CL，fetal membrane thickness，and their combination for predicting preterm delivery was plotted and analyzed，respectively. Results　In the light of the follow-up，47 cases had preterm delivery，and 130 had term delivery. The term delivery group had longer mean CL〔（32.9±4.8） mm vs （24.9±3.1） mm〕，and thinner mean fetal membrane thickness〔（1.19±0.11） mm vs （1.37±0.22） mm〕than preterm delivery group（P<0.05）. There were no statistically significant differences in DVP，and percentages of opening cervical orifice and uterine malformation between the two groups （P>0.05）. Binary Logistic regression analysis showed that shorter CL〔OR=0.612，95%CI（0.510，0.733）〕 and increased fetal membrane thickness〔OR=2.005，95%CI（1.439，2.795）〕were associated with preterm delivery in twin pregnancy（P<0.05）. The AUC of CL，fetal membrane thickness and their combination for predicting preterm delivery in twin pregnancy was 0.914，0.789，and 0.946，respectively，suggesting that the combination of CL with fetal membrane thickness had greater AUC than each of them alone （P<0.05）. Conclusion　Either CL or fetal membrane thickness could effectively predict preterm delivery in twin pregnancy，and the combined application of them may have a higher predictive effect.

Key words: Premature birth；Pregnancy, twin；Cervical length measurement；Fetal membrane thickness；Ultrasonography, prenatal；Diagnosis, differential；Forecasting

摘要： 背景　早产是妊娠最严重且常见的并发症，双胎妊娠早产率更高。有效预测双胎妊娠早产并及时采取相关预防治疗措施将极大地降低早产率及提升新生儿健康状况。目的　评估经阴道超声测量宫颈长度（CL）、经腹部超声测量胎膜厚度及两者联合应用预测双胎妊娠早产的价值。方法　选取2019年9月至2021年1月在郑州大学第二附属医院就诊的177例双胎妊娠孕妇作为研究对象，于孕20~24周测量CL、胎膜厚度及最大羊水池深度（DVP），并观察宫颈内口开放情况，结合既往彩超检查结果判断其子宫是否畸形。根据门诊随访或电话随访追踪到的分娩孕周将研究对象分为早产组和足月产组，比较两组孕妇CL、胎膜厚度、DVP、宫颈内口开放及子宫畸形情况，绘制CL、胎膜厚度分别及联合预测双胎妊娠早产的受试者工作特征（ROC）曲线。结果　依据追踪情况，早产组47例，足月产组130例。足月产组CL长于早产组〔（32.9±4.8）mm与（24.9±3.1）mm〕，胎膜厚度薄于早产组〔（1.19±0.11）mm
与（1.37±0.22）mm〕（P<0.05）；两组DVP、宫颈内口开放比例、子宫畸形比例比较，差异无统计学意义（P>0.05）。二元Logistic回归分析结果显示，CL〔OR=0.612，95%CI（0.510，0.733）〕、胎膜厚度〔OR=2.005，95%CI（1.439，2.795）〕是双胎妊娠早产的影响因素（P<0.05）。CL、胎膜厚度分别及联合预测双胎妊娠早产的ROC曲线下面积（AUC）分别为0.914、0.789、0.946。CL联合胎膜厚度预测双胎妊娠早产的AUC大于两者单独预测双胎妊娠早产的AUC（P<0.05）。结论　CL及胎膜厚度可有效预测双胎妊娠早产，且联合应用时预测效能更高。

关键词: 早产；妊娠, 双胎；宫颈长度测量；胎膜厚度；超声检查, 产前；诊断, 鉴别；预测