Oral contraceptives (either combined or progesterone only) Injectable progesterone Levonorgestrel implants Estrogenic vaginal ring Percutaneous contraceptive patches Intrauterine device (IUD) or intrauterine system (IUS) with a documented failure rate of <1% per year Male partner sterilization (vasectomy with documentation of azoospermia) prior to the female subject's entry into the study; this male must be the sole partner for the subject Double barrier method: condom and an occlusive cap (diaphragm or cervical/vault caps) with a vaginal spermicidal agent (foam/gel/film/cream/suppository).