Does Extended Exposure to Estrogen Raise Risk for Clot?

Estrogen-containing contraception raises risk for thromboembolic disease but is still considered safe for most women of reproductive age. To examine whether risk for venous thromboembolism (VTE) is increased with use of combined oral contraceptives (COCs) containing ethinyl estradiol and levonorgestrel in extended (84/7 day) or continuous (365/0 day) cycles compared with traditional (21/7 day) cycles, researchers analyzed retrospective data from 733,000 U.S. women who were commercially insured between 2007 and 2015.

Compared with cyclic COC use, continuous/extended COC use was associated with a slightly elevated risk for VTE. However, the absolute difference in incidence between the propensity score–matched cohorts was 0.35 cases per 1000 pe…