Abstract: Objective To study the prediction of expected date of confinement by cervical maturity evaluated by ultrasound elastography. Methods A total of 176 pregnant women who met the inclusion requirements were divided into two groups according to the time to onset of labor （TOL）, TOL ≤ 1 week group （96 cases） and TOL>1 week group （80 cases）. The general data, cervical length, cervical width, height of fetal exposure, depth of embedded amniotic cavity, and B/A value of two groups were recorded by abdominal ultrasound and elastography. Univariate analysis was used to find out the indicators that affect the TOL. Multiple logistic analysis was used to identify independent influencing factors for TOL. ROC curve was used to analyze the potential prediction efficiency of each index. Results Cervical length, height of fetal exposure, and B/A value were independent influencing factors for predicting TOL （P<0.05）. The area under curve （AUC） of cervical length, height of fetal exposure, B/A value, and their combination were 0.740, 0.743, 0.817, and 0.903, respectively. The AUC of the combination of the three indicators was the highest, followed by B/A value, while height of fetal exposure and cervical length were the lowest in AUC. The best diagnosis point for TOL of B/A value was 1.325, the sensitivity was 50%, and the specificity was 95.8%. The sensitivity of the combination was 98.8%, and the specificity was 62.5%. Conclusion B/A value could be used as one of the indicators for predicting TOL, and the combination of cervical length, height of fetal exposure, and B/A value could improve the accuracy of the prediction, and provide guidance for clinical labor prediction.

Key words: Ultrasound elastography, Cervical maturity, Time to onset of labor, B/A value