Universal cervical length screening and risk of spontaneous preterm birth: a systematic review and meta-analysis.

OBJECTIVE: To evaluate the risk of spontaneous preterm birth (sPTB) with or without universal transvaginal ultrasound (TVU) cervical length (CL) screening at the time of mid-trimester scan.

DATA SOURCES: Medline, Embase, ClinicalTrials.gov and Web of Science were systematically searched from the inception of the databases to November 12th, 2023 utilizing combinations of the relevant medical subject heading (MeSH) terms, keywords, and word variants that were considered suitable for the topic.

STUDY ELIGIBILITY CRITERIA: Studies including individuals with singleton gestations at 16-25 weeks of gestation screened or not screened with universal TVU CL screening were considered eligible. Primary outcome was sPTB <37 weeks; secondary outcomes were sPTB <34 and <32 weeks.

STUDY APPRAISAL AND SYNTHESIS METHODS: Random effect head to-head meta-analyses was used to directly compare each outcome, expressing the results as summary odds ratio (OR) and relative 95% confidence interval (CI). The quality of the included studies was independently assessed by two reviewers, using the NOS scale for cohort studies and ROB2 Tool for randomized controlled studies. The study was registered on PROSPERO database (CRD42022385325).

RESULTS: Eight studies, including n=447,864 pregnancies, were included in the meta-analysis (n=213,064 screened with TVU CL, n=234,800 unscreened). In the overall analysis, universal TVU CL did not significantly decrease the sPTB rates < 37 weeks (OR 0.92, 95%CI 0.84-1.01, p=0.07) and < 34 weeks (OR 0.87 95%CI 0.73-1.04, p=0.12), but was significantly associated with a lower risk of sPTB < 32 weeks (OR 0.84 95%CI 0.76-0.94, p=0.002). Individuals without a prior sPTB had a significant lower risk of sPTB < 37 weeks (OR 0.88, 95%CI 0.79-0.97, p=0.01) and a lower trend of sPTB < 32 weeks (OR 0.82, 95%CI 0.66-1.01, p=0.06) when screened with TVU CL, compared to no screening.

CONCLUSION: Universal TVU CL screening usually < 24 weeks in singletons without a prior SPTB is associated with a significant reduction in SPTB < 37 weeks, compared to no screening.