Incidence of neonatal venous thromboembolism: a systematic review and meta-analysis of the literature

Background: Venous thrombosis is increasingly reported in neonates, but contemporary estimates of its incidence are missing. Objectives: To determine the incidence of venous thromboembolism in neonates. Methods: A literature search was performed for peer-reviewed publications (1990-2024). We included peer-reviewed studies describing incidence of venous thrombosis in neonates up to 44 weeks of corrected gestational age. Risk of bias in included studies was assessed using the “risk of bias in nonrandomized studies—of interventions” tool. We performed a meta-analysis for all included studies and stratified by comorbidities, thrombosis location, study design, and use of thrombosis screening. Publication bias was assessed using funnel plot and regression test for funnel plot asymmetry. Results: The literature search retrieved 10,862 studies, of which 82 were included in this review (N = 3,461,607 neonates). Most studies (98%) included neonates admitted to the neonatal intensive care unit, and several studies focused further on neonates with additional comorbidities such as congenital heart disease or prematurity. Overall, the cumulative incidence of venous thrombosis was 10.6% (95% CI, 7.5%-13.7%). Reported incidences of thrombosis were higher in studies focusing on neonates with cardiac disease and on catheter-related and portal thrombosis. Prospective studies and studies using surveillance imaging also reported higher rates of thrombosis. Conclusion: Venous thrombosis is frequent among neonates hospitalized in neonatal intensive care units, but its frequency appears to be highly variable depending on the population studied, whether clinically unsuspected thromboses are considered, and study design. Future work is urgently needed to prevent thrombosis in this population.