Serial Cervical Length Measurement for Determining the Risk of Preterm Labor: A Prospective Study

Objective: This study aimed to evaluate whether serial evaluations of cervical length (CL) have the potential to determine preterm labor in women with threatening preterm labor (TPL). Materials and Methods: This prospective study included pregnant women at 24 to 37 weeks of gestation referred to our institute because of TPL. Cervical length was measured at three successive time points using transvaginal sonography (upon admission, one-, and two-weeks post-admission). Data were analyzed using both parametric and non-parametric statistics. Results: The mean age of the 126 patients included was 25.60 ± 6.48 years, with age ranging from 14 to 42 years. The mean pregnancy age, at the time of the sonogram, was 33.54 ± 2.78 weeks. The initial CL had an area under the receiver operating characteristic curve (AUROC) of 0.854. The CLs measured one and two weeks later had AUROCs of 0.868 and 0.870, respectively. Based on these data, the cut-off points of 28.5 and 27.5 mm were identified for the initial and subsequent two-week CL measurements, respectively, capable of predicting preterm delivery. If the CL measured at initial admission was >28.5 mm, the likelihood of timely delivery was 92.22%. However, if the CL measured at initial admission was <28.5 mm, the chance of premature preterm delivery increased by 2.3 times. Patients with a CL <27.5 mm in the second week were 18.75% more likely to have a preterm delivery. If the CL was >27.5 mm, the probability of timely delivery was 89.7%. Conclusion: In this cohort of women, serially measured CLs taken during transvaginal sonography demonstrated promise as a method for indicating the possible risk of preterm delivery. Thus, measured CL may be a useful diagnostic component for prenatal care, as well as for classifying the risk of preterm delivery. Nevertheless, further studies are required to confirm the effectiveness and safety of these sonographic measures in larger and more diverse patient cohorts.