Predicting Preterm Birth in Low-Risk Singleton Pregnancies: A New Approach

Preterm birth is a major cause of neonatal morbidity and mortality. Even women with no known risk factors for preterm birth can be affected, highlighting the need for reliable predictive measures.

A prospective study was conducted to assess the predictive value of the uterocervical angle and cervical length for spontaneous preterm birth in 1107 singleton pregnant women between 16+0 and 23+6 weeks of gestation at low risk for spontaneous preterm birth.1 The study was conducted between September 2020 and September 2021. Cervical length and the uterocervical angle were measured using transvaginal ultrasonography. The patients were monitored until delivery to assess the occurrence of spontaneous preterm birth before 37 weeks of gestation, which was the primary pregnancy outcome.

Results published in the Archives of Gynecology and Obstetrics show that a uterocervical angle ≥ 99° predicted spontaneous preterm birth before 37 weeks, with a sensitivity of 91% and a specificity of 76%. In contrast, a cervical length ≤ 33.8 mm predicted preterm birth before 37 weeks with a lower sensitivity of 25% and a specificity of 66%.

Combining uterocervical angle ≥ 99° with a cervical length ≤ 33.8 mm, yielded a sensitivity of 66%, specificity of 93%, positive predictive value of 36%, likelihood ratio of 9, and overall accuracy of 91% in predicting spontaneous preterm birth. This combination significantly improved specificity while maintaining an acceptable reduction in sensitivity compared to cervical length alone.

This study shows that in addition to cervical length, the uterocervical angle is a valuable ultrasound parameter for predicting spontaneous preterm birth in low-risk singleton pregnancies. The combination of both the uterocervical angle and cervical length resulted in stronger predictive values for spontaneous preterm birth compared to using cervical length alone.

Reference

1.   Nguyen TTH, et al. Uterocervical angle and cervical length measurements for spontaneous preterm birth prediction in low-risk singleton pregnant women: a prospective cohort study. Arch Gynecol Obstet. 2024 Sep;310(3):1611-1619. doi: 10.1007/s00404-024-07646-4.