Are factor V Leiden carriers who use oral contraceptives at extreme risk for venous thromboembolism?

Eur J Contracept Reprod Health Care. 2000 Jun;5(2):105-12. doi: 10.1080/13625180008500383.


Background: Major concern was raised by an earlier study regarding oral contraceptive use in women with the factor V Leiden mutation. A more than 30-fold increase in relative risk for venous thromboembolism was reported; for homozygotes, the relative risk was as much as 100-fold or more.

Objective: To replicate the reported risk estimates with a new population-based case-control study.

Methods: Eighty women with a diagnosis of venous thromboembolism were consecutively identified and compared with population-based controls (n = 406). Factor V Leiden mutation was identified by genotype analysis. The evaluation was performed with conditional logistic regression (matched for 5-year age group).

Results: Matched, adjusted odds ratios (OR) for idiopathic venous thromboembolism in women without and with the factor V Leiden mutation who used oral contraceptives were 4.1 (95% confidence interval (CI) 2.1-7.8) and 10.2 (95% CI 1.2-88.4), respectively. The adjusted OR for factor V Leiden carriers was 2.0 (95% CI 1.0-4.4). The OR for women with the factor V Leiden mutation and oral contraceptive use versus no factor V Leiden mutation and no oral contraceptive use was 10.2 (95% CI 3.8-27.6).

Conclusion: The results confirm the increased relative risk of idiopathic venous thromboembolism for users of oral contraceptives and factor V Leiden carriers. However, we suspect that the true risk for women who are factor V Leiden carriers may be increased two- to four-fold rather than seven-fold or more, and that the risk for the combination of factor V Leiden and oral contraceptive use may be increased in the order often- to 15-fold rather than over 30-fold.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Case-Control Studies
  • Cohort Studies
  • Contraceptives, Oral / adverse effects*
  • Contraindications
  • Factor V / genetics*
  • Female
  • Genetic Predisposition to Disease
  • Germany / epidemiology
  • Heterozygote*
  • Humans
  • Middle Aged
  • Odds Ratio
  • Risk
  • Thromboembolism / chemically induced*
  • Thromboembolism / epidemiology
  • Thromboembolism / genetics
  • Venous Thrombosis / chemically induced*
  • Venous Thrombosis / epidemiology
  • Venous Thrombosis / genetics


  • Contraceptives, Oral
  • Factor V