Preterm birth rates and risk factors among women with cervical incompetence undergoing prophylactic cerclage: a systematic review and meta-analysis

Preterm birth is the leading cause of neonatal mortality and long-term health complications. Cervical cerclage (CC) represents a critical intervention for extending pregnancy duration and enhancing neonatal survival in patients diagnosed with cervical insufficiency. The aim of this study was to identify risk factors for preterm birth through a meta-analysis comparing outcomes between preterm and full-term deliveries following non-emergency CC. PubMed, EMBASE, Cochrane Library, Web of Science (WOS), and Scopus were searched to identify studies fulfilling predefined inclusion and exclusion criteria on 31 March 2025. The primary outcome measure was the preterm birth rate, which was calculated as the proportion of preterm birth cases in the total sample size. The impact of various risk factors on preterm birth was further analysed. A total of 45 studies were included, and the meta-analysis revealed that the aggregate preterm birth rate at 37 weeks was approximately 48.09% following CC. Compared with twin pregnancies, singleton pregnancies were associated with a lower risk of preterm birth (odds ratio [OR]: 0.71; 95% CI: 0.55-0.91; p = 0.008). Among surgery-related factors, CC indicated by physical examination poses a greater risk. Short cervical length prior to CC and elevated inflammatory markers, such as C-reactive protein (CRP), were significantly associated with preterm birth (OR: 0.79; 95% CI: 0.66-0.95; p = 0.011). This study identified critical risk factors for preterm birth following CC, including physical examination indications, a cervical length ≤ 1.5 cm, cervical dilatation, and CRP abnormalities. These findings are instrumental in identifying high-risk individuals and guiding effective medical resource allocation. However, due to study limitations, large-scale studies with multiple PTB cut-off timepoints and comprehensive analyses of risk factors are necessary to refine preventive and therapeutic approaches for preterm birth.