Predictive value of cervical length measured after 24 weeks for spontaneous preterm birth: systematic review and meta-analysis

OBJECTIVE: weeks of gestation between women with spontaneous preterm birth and term birth and the predictive accuracy of third trimester transvaginal cervical length in the prediction of spontaneous preterm birth among asymptomatic women. DATA SOURCES: A systematic search of published literature was performed in PubMed, MEDLINE, and the Cochrane Library through June 2025. There was no language restriction. STUDY ELIGIBILITY CRITERIA: weeks of gestation in asymptomatic women with both spontaneous preterm birth and term births that allowed the construction of 2×2 contingency tables were included. We excluded abstracts, studies with duplicated data, symptomatic women, twin pregnancies, or transabdominal cervical length measurement (International Prospective Register of Systematic Reviews registration number: CRD42024538449). STUDY APPRAISAL AND SYNTHESIS METHODS: T.S.T.A. and T.Y.P.C. searched for and selected studies independently. Newcastle-Ottawa Scale was used to evaluate the quality of the included studies. Mean differences in transvaginal cervical length measurements between spontaneous preterm birth and term populations were calculated using the inverse variance method with the random-effects model. Subgroup analyses on gestational age, transvaginal cervical length measurement technique, populations, and type of cohort studies were performed. Predictive accuracy of various transvaginal cervical length cutoffs was evaluated using the DerSimonian-Laird random-effects model. Youden index was calculated to identify the optimal transvaginal cervical length cutoff. RESULTS: weeks had the highest positive likelihood ratio of 7.75 to predict spontaneous preterm birth, with pooled sensitivity of 0.74, specificity of 0.92, negative likelihood ratio of 0.31, and diagnostic odds ratio of 28.1. CONCLUSION: weeks may be used to identify women at risk of spontaneous preterm birth.