A predictive model of short cervix at 20–24 weeks using first‐trimester cervical length measurement and maternal history

AbstractObjectivesTo develop a model for the prediction of short cervix ( ≤ 15 mm) at 20–24 weeks by combining maternal history and transvaginal ultrasonographic measurement of cervical length at 11–14 weeks. To explore the value of an additional ultrasound examination of the cervix at about 17 weeks.MethodsLongitudinal prospective study in 800 unselected pregnant women presenting for first‐trimester ultrasound assessment by nuchal translucency and serum biochemistry. Cervical length was evaluated transvaginally between 11 weeks and 13 weeks and 6 days (cx1), at 16–19 weeks (cx2) and 20–24 weeks (cx3). Backward multiple logistic regression analysis with cx3 ≤ 15 mm as the dependent variable was used to identify the predictors of a short cervix at 20–24 weeks.ResultsCx1 and history of preterm delivery were significant independent contributors of a short cervix at 20–24 weeks [area under the curve (AUC 0.808, p < 0.001, Model) 1]. Furthermore, the cx1/cx2 ratio was a significant independent predictor of a short cervix at 20–24 weeks (odds ratio = 58.325 p = 0.012). The addition of the cx1/cx2 ratio improved the model (AUC = 0.878, p < 0.001, Model 2).ConclusionsA short cervix at 20–24 weeks can be predicted at the 11–14 weeks scan. The addition of a cervical measurement at about 17 weeks can improve the prediction model. Copyright © 2011 John Wiley & Sons, Ltd.