The Association of Second-Trimester Cervical Length With Mode of Delivery [ID 2683533

Abstract

INTRODUCTION: Second-trimester transvaginal cervical length (TVCL) under 2.5 cm is a well-established risk factor for preterm birth and mid-trimester loss. However, few studies have investigated birth outcomes associated with increasing lengths of “normal” TVCL (2.5 cm or greater). We aimed to evaluate the association of normal TVCL tertiles with mode of delivery. METHODS: This is a retrospective cohort study of patients eligible for vaginal birth with singleton term gestations and normal TVCL (at 16–24 weeks of gestation) delivering at a tertiary care center from June 2022 to June 2023. Mode of delivery was compared by TVCL tertiles: T1, 2.5–3.49 cm; T2, 3.5–4.49 cm; and T3, 4.5 cm or greater. Multivariable logistic regression controlled for potential confounders. Institutional review board approval was obtained. RESULTS: Of 1,033 eligible deliveries, 175 (16.9%), 621 (60.1%), and 237 (22.9%) had TVCL in T1, T2, and T3, respectively. Compared to patients with TVCL in T1, those in T2 and T3 were significantly more likely to have an intrapartum cesarean delivery (CD) (T1 3.4% versus T2 8.5%, P=.02; T3 11.8%, P=.002), with odds ratios (ORs) of 2.63 (CI, 1.1–7.6) and 3.77 (CI, 1.5–11.4), respectively. After adjusting for confounders, those with TVCL in T3 remained statistically more likely to undergo CD than those in T1, adjusted OR 6.7 (CI, 2.3–19.2). Of note, no patients with TVCL in T1 had CD for Stage 1 arrest. CONCLUSION: Patients with longer TVCL at 16–24 weeks are significantly more likely to undergo an intrapartum CD. This association can be considered during patient counseling on delivery outcome expectations.