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

OBJECTIVES

To 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.

METHODS

Longitudinal 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.

RESULTS

Cx1 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).

CONCLUSIONS

A 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.