First-trimester cervical length screening and the risk of preterm birth: a systematic review and meta-analysis.

BACKGROUND

The clinical utility of first-trimester cervical length (CL) measurement remains uncertain. This systematic review and meta-analysis aimed to evaluate the association between first-trimester CL measurement and preterm birth (PTB) risk.

METHODS

This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered in PROSPERO (CRD42023462610). A comprehensive search was conducted across four electronic databases (PubMed, Scopus, Web of Science, and Cochrane Library) until January 29, 2024, using MeSH terms and keywords. We included randomized controlled trials, comparative observational studies, and retrospective studies that examined first-trimester CL measurement and reported PTB as a primary or secondary outcome. Two independent reviewers conducted study selection and data extraction, resolving discrepancies through discussion. Risk of bias was assessed using the Newcastle-Ottawa Scale. A meta-analysis using a random-effects model was conducted, with heterogeneity evaluated via I² statistics.

RESULTS

Five studies comprising 16,053 pregnancies were included. CL was significantly shorter in individuals delivering before 34 weeks compared to those delivering at or after 34 weeks, with a pooled mean difference of -0.59 mm (95% confidence interval [CI]: -1.14 to -0.04; p = 0.04; I²=72.56%). Similarly, those delivering before 37 weeks had a significantly shorter CL than those delivering at or after 37 weeks, with a pooled mean difference of -0.23 mm (95% CI: -0.43 to -0.03; p = 0.02; I²=76.26%).

CONCLUSION

First-trimester CL measurement is significantly associated with PTB risk. However, due to study heterogeneity and physiological variability in early pregnancy, its clinical utility as a predictive tool remains uncertain. Further research with standardized protocols and larger cohorts is needed to assess its role in screening and early intervention strategies for both low- and high-risk pregnancies.