Risk Factors of Velamentous Cord Insertion in Singleton Pregnancies-A Systematic Review and Meta-Analysis

Objective: This meta-analysis aims to quantitatively summarize current data on various potential risk factors of velamentous cord insertion (VCI). A better understanding of these risk factors could enhance prenatal identification both in settings with routine screening and in those where universal screening for cord insertion anomalies is not yet recommended. Methods: A systematic search was conducted in MEDLINE, Cochrane Library, and Scopus from their inception until 7 February 2024. Eligible studies included observational studies of singleton pregnancies with VCI, identified either prenatally or postnatally, compared with pregnancies with central or eccentric cord insertion. Analyses were performed using DerSimonian and Laird random-effects models, with outcomes reported as risk ratios (RR) or mean differences with 95% confidence intervals (CI). Results: In total, 14 cohort and 4 case-control studies were included, reporting on 952,163 singleton pregnancies. Based on the cohort studies, the overall prevalence of VCI among singleton pregnancies was calculated to be 1.54%. The risk of VCI was significantly higher among pregnancies conceived using assisted reproductive technology (RR, 2.32; 95% CI: 1.77-3.05), nulliparous women (RR, 1.21; 95% CI: 1.15-1.28), women who smoked (RR, 1.14; 95% CI: 1.08-1.19), and pregnancies diagnosed with placenta previa (RR, 3.60; 95% CI: 3.04-4.28). Conclusions: This meta-analysis identified assisted reproductive technology, nulliparity, smoking, and placenta previa as significant risk factors of VCI among singleton pregnancies. These findings could inform screening policies in settings where universal screening for cord insertion is not routinely performed, suggesting a targeted approach for women with these specific risk factors.