In the Women's Health Initiative, combined estrogen-progestin replacement therapy was associated with a significant increase in pulmonary embolism (eight more pulmonary emboli per 10,000 person-years; HR 2.13, unadjusted 95% CI 1.39-3.25).
Data from: Rossouw JE, Anderson GL, Prentice RL, et al. Risks and benefits of estrogen and progestin in healthy postmenopausal women: Principal results from the Women's Health Initiative randomized controlled trial. JAMA 2002; 288:321.