Departments of Obstetrics and Gynecology, University of Colorado School of Medicine, Aurora, Colorado; and The Ohio State University Wexner Medical Center, Columbus, Ohio.
Obstet Gynecol. 2013 Feb;121(2 Pt 1):260-264. doi: 10.1097/AOG.0b013e31827d8e1b.
To evaluate whether women with known risk factors for preterm birth will manifest different rates of cervical shortening preceding a spontaneous preterm birth.
We conducted a secondary analysis of data from the Maternal--Fetal Medicine Units Network Preterm Prediction Study. Known risk factors for preterm birth were recorded. Cervical lengths were measured between 22+0 weeks and 24+6 weeks, and again 4 weeks later. Cervical slope was defined as the change in cervical length between these visits divided by time (millimeters per week). Preterm birth was defined as preterm premature rupture of membranes or spontaneous preterm labor leading to delivery before 37 weeks of gestation. We analyzed the data for 2,584 women using logistic regression and tested for interaction between risk factors in the model to determine whether cervical shortening preceded preterm births in all variable groups.
Cervical slope was not significantly associated with preterm birth (P=.9) in women with vaginal bleeding. Cervical slope was significantly associated with preterm birth in women without a history of vaginal bleeding (odds ratio 1.2, 95% confidence interval 1.1-1.4).
Pregnancies without vaginal bleeding have a 20% increase in the risk of preterm birth for each additional millimeter per week increase in cervical slope. Pregnancies with vaginal bleeding are at risk for preterm birth but do not appear to undergo progressive cervical shortening. This suggests that women with vaginal bleeding undergo a different mechanism leading to preterm birth.
II.
评估已知早产风险因素的女性在自发性早产前是否会出现不同的宫颈缩短率。
我们对母体-胎儿医学单位网络早产预测研究的数据进行了二次分析。记录了早产的已知风险因素。在 22+0 周到 24+6 周之间以及 4 周后再次测量宫颈长度。宫颈斜率定义为两次就诊时宫颈长度的变化除以时间（每周毫米数）。早产定义为胎膜早破或自发性早产导致妊娠 37 周前分娩。我们使用逻辑回归分析了 2584 名女性的数据，并在模型中测试了风险因素之间的相互作用，以确定在所有变量组中宫颈缩短是否先于早产。
在有阴道出血的女性中，宫颈斜率与早产无显著相关性（P=.9）。在无阴道出血史的女性中，宫颈斜率与早产显著相关（比值比 1.2，95%置信区间 1.1-1.4）。
宫颈斜率每周增加 1 毫米，无阴道出血的妊娠早产风险增加 20%。有阴道出血的妊娠有早产风险，但似乎不会经历宫颈逐渐缩短。这表明阴道出血的女性发生早产的机制不同。
II。
