Abstract
Purpose Preterm birth is the leading cause of early neonatal morbidity and mortality. Strategies to predict preterm birth risk can help improve pregnancy outcomes. Even pregnant women without known risk factors for preterm birth can also experience it. This study aimed to evaluate the ability of the uterocervical angle and cervical length to predict preterm birth in low-risk singleton pregnant women. Methods A prospective study of 1,107 singleton pregnant women between 16+ 0 and 23+ 6 weeks gestation at low risk for preterm birth who were treated at the Haiphong Hospital of Obstetrics and Gynecology, Vietnam, between September 2020 and September 2021 was conducted. A single sonographer assessed the cervical length and the uterocervical angle using transvaginal ultrasonography. The patients were followed up until delivery to determine the main pregnancy outcome (preterm birth before 37 weeks gestation). The cut-off points for the uterocervical angle and cervical length were established by analysing the receiver operating characteristic curve. The sensitivity, specificity, likelihood ratio, and positive and negative predictive values of the uterocervical angle and cervical length for predicting preterm birth were determined. Results A uterocervical angle ≥ 98.86° predicted preterm birth at < 37 weeks, with a sensitivity and specificity of 91% and 75.5%, respectively. A cervical length ≤ 33.8 mm predicted preterm birth at < 37 weeks with a sensitivity and specificity of 25% and 66%, respectively. A uterocervical angle ≥ 98.96° combined with a cervical length ≤ 33.8 mm increased the positive predictive value, positive likelihood ratio, and accuracy of preterm birth prediction to 36%, 8.87, and 91%, respectively. Conclusion Compared to the cervical length, the uterocervical angle can be considered a valuable ultrasound parameter for predicting preterm birth in low-risk singleton pregnant women. Combining both the uterocervical angle and cervical length yielded stronger preterm birth prediction values.