This meta-analysis is reported in accordance with PRISMA (preferred reporting items for systematic reviews and meta analyses) guidelines. The supporting PRISMA checklist of this review is available as supporting information, see S1 Checklist.

To identify eligible trials, we conducted a comprehensive search using the online databases PubMed, EMBASE, and Cochrane Central Register of Controlled Trials. The last search was performed on June 1, 2023, without any date restrictions. We employed a combination of relevant keywords and their variations, including “braided suture,“ “Mersilene tape,“ “monofilament suture,“ “suture material,“ “cerclage,“ “preterm birth” and” outcomes.” The search strategy can be found in S2 Appendix. In addition, we reviewed the reference lists of retrieved studies to identify any additional relevant articles.

In this systematic review, we included randomized controlled trials (RCTs), quasi-RCTs, and cohort studies that compared the use of Mersilene tape with other conventional sutures in transvaginal cervical cerclage for the prevention of preterm birth in singleton pregnancies. We included studies involving participants with history-, ultrasound- and physical examination-indicated transvaginal cerclage to prevent preterm birth, as well as any type of cerclage technique (Shirodkar, McDonald, cervicoisthmic). History-indicated cerclage encompassed placement after ≥ 1 prior mid-trimester pregnancy loss or early spontaneous preterm birth (< 28 weeks) suggestive of cervical insufficiency. Ultrasound-indicated cerclage involved placement in women with a history of prior spontaneous preterm birth and ultrasound-confirmed cervical length < 25 mm. Exam-indicated cerclage referred to placement after asymptomatic mid-trimester cervical dilation of ≥ 1 centimeter via digital examination [6]. The studies were required to report on maternal, fetal, or neonatal outcomes and provide data on the occurrence of adverse events. Only studies published in the English language were considered for inclusion in this review.

This review specifically aimed to compare different suture types in conventional transvaginal cervical cerclage. Therefore, other types of cerclage procedures such as abdominal, laparoscopic, and emergency cerclages, as well as replacements of cerclages, were excluded from the analysis. Additionally, twin pregnancies, ongoing trials, case reports, reviews, and animal studies were not included in the tabulation of studies. Meeting abstracts were also excluded unless we were able to obtain complete study data either from the authors or through database publications.

Two independent reviewers (J.T.F. and S.S.W.) conducted data extraction, collecting relevant information for analysis. Any disagreements were resolved through discussion, and in cases where a consensus could not be reached, the article was excluded from the study. The extracted information included the names of the authors, year of publication, sample size, study type, indication for cerclage, cervical length at screening, gestational age at delivery, type of cerclage, and type of suture used.

The primary outcomes of interest were the incidence of PTB at gestational ages < 24, <28, < 32, <34, and < 37 weeks. Secondary outcomes, if available, included the occurrence of preterm premature rupture of membranes (PPROM), infection, chorioamnionitis, and surgical complications within 24 h of the procedure, such as hemorrhage, cervical trauma/lacerations/lesions, as well as neonatal outcomes, including neonatal mortality, fetal mortality, perinatal death, and neonatal intensive care unit (NICU) admission.

Two independent reviewers (J.T.F. and S.S.W.) conducted the critical appraisal process. Any disagreements regarding the risk of bias assessment were resolved through discussion and consensus. In cases where consensus could not be reached, a third reviewer (L.H.P.) was consulted to provide input and help resolve the disagreement.

For the assessment of RCTs, the Cochrane risk of bias tool was utilized. This tool evaluates the risk of bias in key domains such as random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective outcome reporting, and other potential sources of bias. The risk of bias for each domain was judged as either low, high, or unclear.

For cohort studies, the Newcastle-Ottawa Scale (NOS) was employed [9]. The NOS assesses the quality of non-randomized studies by evaluating three key domains: selection of study groups, comparability of groups, and assessment of outcomes. Each study is assigned a star rating based on the quality of these domains, with a higher star rating indicating a lower risk of bias. The included studies were judged as having a high (scores of 0–3), medium (scores of 4–6), or low risk of bias (scores of 7–9), respectively.

A sensitivity analysis was conducted on the primary outcome. This was performed by removing studies with an overall high risk of bias to examine their impact on the effect estimate.

Heterogeneity analysis was performed using the chi-square test, and the results were expressed as the I2 index. A value of 0% indicated the absence of statistical heterogeneity, while higher values indicated increased heterogeneity. A fixed-effects model was applied when heterogeneity was not significant (p > 0.1 and I2 < 50%). When heterogeneity was significant (p < 0.1 and I2 > 50%), a random-effects model was used. Pooled relative risk (RR) and corresponding 95% confidence intervals (CIs) were calculated for dichotomous variables. An RR > 1 indicated an increased risk in the intervention group compared to the control group. Publication bias was evaluated using Egger’s linear regression test, with a p-value < 0.05 considered statistically significant. All statistical analyses were performed using Stata 13.0 (Stata Corporation, College Station, TX) and RevMan Software Version 5.2 (Cochrane Collaboration, Copenhagen, Denmark).