Can sonographic measurements and changes in cervical length during pregnancy predict preterm labour in an asymptomatic low-risk population?

Objective: This study measured cervical length (CL) at 14-16 and 21-24 weeks of gestation and assessed whether the difference between the measurements is predictive of preterm delivery (PTD).

Methods: This retrospective, cohort study included patients with two consecutive CL measured with transvaginal sonography at 14-16 weeks of gestation (CL) and 21-24 weeks (CL). Electronic medical records were reviewed for demographic, medical and obstetric history; complications during the current pregnancy and delivery data. CL, CL and the change between scans were evaluated and correlated to PTD prediction.

Results: Among the 216 patients, 196 (90.7%) delivered at term (≥37 weeks) and 20 (9.3%) preterm (<37 weeks). CL was not a good predictor of PTD (p = .70). CL was significantly shorter in the PTD group (p < .05). The correlation between CL change and PTD was not significant (p = .55). Perinatal outcomes between term and preterm deliveries were similar.

Conclusions: Sonographic measurement of CL at 14- to 16-week gestation and the difference between CL in the first and second scans are not reliable predictors of PTD. However, cervical length at 21-24 weeks in low-risk women is predictive of this complication.