Does a third trimester short cervix or change in cervical length predict preterm delivery?

Abstract

To determine if a short cervical length (CL) defined as < 2.5cm beyond 28 weeks gestation and/or change in CL in patients with risk factors are associated with preterm delivery. This is an IRB exempt, retrospective chart review from 2015 to 2021. It includes all singleton gestations with symptoms/risk factors for preterm delivery who also had a CL evaluation via TVUS at our institution. Primary outcome was preterm delivery where we compared patients with a short CL of < 2.5 cm to those with a normal CL between 28-32 weeks. CL measurements were further categorized into CL < 2.0, < 1.5, and < 1.0 cm. Also, the change in CL between 20 and 28 weeks was determined. Data analysis was performed using t-test and Chi-square analysis for continuous variables and categorical values respectively. Odds ratios with 95% confidence interval were calculated for the primary outcome. Significant values are considered p < 0.05 Among 182 patients with third trimester CL evaluation, 47 patients (25.8%) had a CL < 2.5cm. Baseline demographics between the 2 groups were similar with respect to age, BMI, race, and prior preterm delivery. Table 1 demonstrates that when comparing the cohort with a short CL to a normal CL in the third trimester, no difference in preterm birth was noted at < 37 weeks, OR 1.86 (0.81, 4.28), < 34 weeks, OR 4.53 (0.73, 28.02), and < 32 weeks, OR 2.91 (0.18, 47.52). When evaluating CL < 1.5 cm, this was associated with an increased risk of preterm delivery (36.4% vs 11.7%, p < 0.05). Also, a greater average change in CL between 20 weeks and the third trimester was associated with preterm delivery (0.9 ± 0.94 vs. 0.5 ± 0.87, p < 0.05; Table 2). In singleton pregnancies, a short CL at < 2.5 cm or even less beyond 28 weeks gestational age is not associated with delivery < 37 weeks when compared to those with a normal CL. However, a short CL < 1.5 cm or change in CL of 0.9 cm or more may increase the risk of preterm birth. Larger studies should be done to evaluate this association.View Large Image Figure ViewerDownload Hi-res image Download (PPT)