Pre-Existing and Gestational Diabetes and Risk of Maternal Venous Thromboembolism: A Systematic Review and Meta-Analysis of Observational Studies

Background: Women who are pregnant are at increased risk of venous thromboembolism (VTE), which persists for up to 3 months following childbirth. Diabetes is known to increase the risk of serious cardiovascular outcomes.

Objective: To comprehensively review literature on the extent to which pre-existing or gestational diabetes influences the risk of VTE in both pregnancy and postpartum.

Search strategy: We used Medline, Embase and Google Scholar to identify observational studies published up to 2 November 2023.

Selection criteria: Studies which quantified the relationship between diabetes on antepartum and/or postpartum VTE, and which provide separate data for pre-existing and gestational diabetes.

Data collection and analysis: Results were pooled, where appropriate, using random-effects meta-analysis.

Main results: Twenty one studies from Europe, the United States and Asia were included. There was an increased risk of antepartum VTE in women with gestational diabetes (RR = 2.48, 95% CI 1.47 - 4.16, I²= 45%, 4 studies) but not pre-existing diabetes (RR = 1.71, 0.43 - 6.77, I²= 68%, 2 studies). For postpartum VTE, there was no clear association with either pre-existing (RR = 1.28, 0.73 - 2.24, I²= 73%, 6 studies) or gestational (RR = 1.39, 0.77 - 2.51, I²= 70%, 10 studies) diabetes.

Conclusions: Our results will provide some reassurance for pregnant women with pre-existing or gestational diabetes, owing to no clear evidence of an increased risk of maternal VTE. While some studies report a raised risk of VTE during antepartum specifically, results must be interpreted in light of high levels of heterogeneity.