Evaluating cervical length as a predictor of preterm labour in women with congenital uterine anomalies – an observational study

Background Women with congenital uterine anomalies (CUA) are at increased risk for spontaneous preterm birth (sPTB). Cervical length surveillance is commonly used to identify cervical shortening as a predictor of sPTB. However, evidence supporting its predictive value in women with CUA remains limited. This study aims to evaluate the effectiveness of cervical length surveillance in predicting sPTB in women with CUA.Methods This retrospective observational study included women with CUA diagnosed on imaging who attended the preterm birth prevention clinic between 2020 and 2024. Singleton pregnancies without additional risk factors for sPTB were included. Cervical length was measured by transvaginal ultrasound between 16 and 24 weeks of gestation. The primary outcome was sPTB before 37 weeks’ gestation. Logistic regression analysis and receiver operating characteristic (ROC) curve analyses were performed to assess the association between cervical length and sPTB and its predictive value.Results Of 502 women referred to the preterm birth prevention clinic, 49 had CUA as their only risk factor for preterm birth. Five women (10.2%) experienced sPTB, and all had normal cervical length measurements. Cervical shortening (<25 mm) was identified in only one woman (2.0%), who subsequently delivered at term following cervical cerclage insertion. The prevalence of sPTB was highest among women with a unicornuate uterus (33.3%), followed by those with a septate uterus (11.1%) and a bicornuate uterus (9.1%). Logistic regression analysis demonstrated no association between cervical length and sPTB (OR 0.97, 95% CI 0.78–1.19; p = 0.75). ROC curve analysis showed poor predictive performance (AUC 0.57, 95% CI 0.31–0.84).Conclusion While cervical length surveillance showed limited predictive value of sPTB in this cohort, the low incidence of cervical shortening precludes definitive conclusions. Larger prospective studies are required to clarify the role of cervical length surveillance in this high-risk group.