The Effect of Protease Inhibitors on the Pharmacokinetics of Oral Norethindrone Contraception

The purpose of this study is to learn if women taking the atazanavir and ritonavir have lower levels of a birth control medication called norethindrone. Norethindrone (also called the mini pill) is an FDA (Food and Drug Administration) approved progestin-only birth control pill used to prevent pregnancy. Norethindrone is the standard medication used in women who take the progestin only pill to prevent pregnancy. There are other birth control pills which contain different medications. The investigators want to learn if HIV medications (atazanavir and ritonavir) make the blood level of this birth control pill higher or lower. If the levels of norethindrone are too low it may not work to prevent pregnancy. The investigators also hope to learn about changes in the vaginal fluids and cervical fluids when women are taking this birth control pill.