The Impact of Obesity on the Risk of Venous Thromboembolism in Users of Combined Oral Contraceptives: A Comprehensive Literature Review

Background: Combined oral contraceptives (COCs) are a widely used method of birth control in the U.S., particularly among women aged 15–44. COCs are known to increase the risk of venous thromboembolism (VTE). Obesity, which affects over 40% of adult women in the U.S., is also a recognized independent risk factor for VTE. However, the compounded risk posed by the simultaneous presence of obesity and COC use has not been thoroughly explored. Hypothesis: Obesity significantly elevates the risk of VTE in women using COCs, demonstrating a synergistic interaction between these two factors. Methods: A systematic literature review was conducted using PubMed, Embase, and Scopus. The search included clinical trials, cohort studies, and peer-reviewed articles from the last 25 years examining the relationship between COC use, obesity, and VTE. Results: Findings indicate a strong positive correlation between BMI and VTE risk in COC users. One meta-analysis reported a baseline VTE incidence of 39.4 per 100,000 woman-years among COC users, with progressively increasing odds ratios (ORs) for higher BMI categories. Women with a BMI ≥35 had an OR of 3.1 compared to those with a BMI of 20–24.9. Another study showed VTE risk increasing up to 24-fold in obese COC users compared to non-obese non-users. Conclusion: Obesity amplifies the thrombotic risk associated with COC use. These findings underscore the importance of personalized contraceptive counseling and targeted preventive strategies for obese women to reduce VTE risk.