Two products combining conjugated estrogens with medroxyprogesterone acetate (Prempro and - Wyeth-Ayerst) were recently approved for marketing by the US Food and Drug Administration. Both combine in one package tablets of Premarin, a conjugated equine estrogen product, with tablets of Cycrin, a medroxyprogesterone acetate brand. With Prempro, both tablets are taken daily continuously; with Premphase, the estrogen is taken daily, but the progestin is taken sequentially on days 15 through 28 of each 28-day cycle.

Two types of oral contraceptives are available in the USA: combination oral contraceptives that contain both an estrogen and a progestin, and progestin-only contraceptives, or "mini-pills."Used as directed, all oral contraceptives marketed in the USA are similarly effective in preventing pregnancy.