Analysis of pregnancy outcomes in patients undergoing ultrasound-indicated cerclage and identification the influence factors for predicting preterm birth: A retrospective study of 87 cases.

OBJECTIVE

To investigate the factors influencing preterm birth in patients after ultrasound-indicated cerclage with different cervical lengths (CL), and explore the optimal cut-off value of CL.

MATERIALS AND METHODS

The retrospective study included 87 pregnant women with a history of preterm birth and second-trimester loss that received ultrasound-indicated cerclage in our hospital between January 2004 and April 2021. Groups were divided by CL at the demarcation point of 1.0, 1.5 and 2.0 cm respectively. The pregnancy outcomes were compared. Logistic regression analysis was performed to assess the independent influence factors. Receiver-operating characteristic (ROC) curves were constructed and the area under the curve (AUC) was used to compare the prediction capability of the associated factors.

RESULTS

Significant difference was found in terms of patients delivered at ≥32 weeks of gestation (19 [55.9%]vs. 41 [77.4%], p < 0.05) and neonatal birth weight (2495 [1138,3185]vs. 2995 [2155,3235] g, p < 0.05), when the CL was categorized at the demarcation point of 1.5 cm. Body mass index (BMI) (odds ratio [OR] = 1.224, p < 0.05), a history of preterm birth and second-trimester loss (OR = 3.153, p < 0.05), and C-reactive protein (CRP) > 5 mg/L (OR = 8.097, p < 0.05) were independent risk factors for gestational age more than 28 weeks. The AUC of joint predictor A included those factors was 0.849 (95% CI: 0.701-0.998, p < 0.05). CRP>5 mg/L was found to be a significant independent risk factor for different gestational age at delivery.

CONCLUSIONS

A CL of 1.5 cm was the optimal cut-off value that could help women who underwent serial CL surveillance choose ultrasound-indicated cerclage at an appropriate time. High BMI, more history of preterm birth and second-trimester loss and abnormal CRP could be used as combined predictors to recognize the risk of preterm birth (<28 weeks) post-surgery.