Cervical length and the risk of spontaneous labor at term

Objective: To investigate the relationship between cervical length (CL) at 37 to 40 weeks and delivery within 7 days and delivery by 41 weeks. Study design: We performed transvaginal ultrasound to measure CL in women with singleton gestations at 37 to 40 weeks. We then used a receiver operating characteristic curve (ROC) to assess the relationship between CL and delivery within 7 days and delivery by 41 weeks. Result: For the 120 women included in the analysis, the mean CL (±s.d.) was 25.3±9.8mm. The logistic regression model to predict each of the outcomes includes gestational age at ultrasound (GA-US) and CL. Neither birthweight, nor parity seems to affect the probability of delivery within 7 days. The ROC curve was used to assess the probability of spontaneous labor within 7 days at each CL measurement. The likelihood ratio of delivery within 7 days when CL is ≤10mm is 12. Conclusion: CL measurement at 37-40 weeks is an independent predictor of delivery within 7 days and delivery by 41 weeks regardless of GA-US. This information can be utilized when counseling patients regarding the management of term pregnancies.