The role of cervical length measurement at 11-14 weeks for the prediction of preterm delivery.

Objective: To determine whether cervical length (CL) measurement at 11?14 weeks is predictive of preterm delivery (PTD).

Methods: This was a prospective study of a low-risk population of 1113 women, who underwent CL measurement at 11-14 weeks. Mean CL was calculated for deliveries at >37, <37 and <34 weeks. Cut-off limits of 27 mm and 30 mm were used to examine the predictive value of CL.

Results: Mean +/- SD CL for the entire study population was 40.6 +/- 5.5 mm. CL was analyzed for term and PTD (<37 weeks) and further analyzed for deliveries at 34-37 and <34 weeks. Mean CL was 38.9 +/- 5.5 mm for PTD and 40.8 +/- 5.5 mm for deliveries >37 weeks (p=0.001). Receiver operating characteristic analysis showed small predictive value of CL for PTD <37 weeks (sensitivity = 63.3% and specificity = 51.1%, area under the curve (AUC)=0.60, 95% CI: 0.54-0.66) (p=0.001) and did not show any predictive value for PTD <35 weeks (AUC=0.55, 95% CI: 0.43-0.67, p=0.355) or PTD <32 weeks (AUC=0.51, 95% CI: 0.30-0.74, p=0.851).

Conclusion: CL at 11-14 weeks does not appear to be predictive of PTD. Statistical analysis of CL did not show any predictive value for PTD <35 weeks, or <32 weeks and although it showed a predictive value for PTD at <37 weeks, the sensitivity was very low.