Interactions Between Antiretrovirals (ARVs) and Combined Oral Contraceptives (COCs)

Inclusion Criteria: * Willing to provide informed consent * Willing to take COCs and follow all study requirements * Has regular menstrual cycles every 21-35 days (when not taking hormonal contraception) * Last menstrual period (LMP) \<35 days before study entry * Has body mass index of 18-30 * Negative urine pregnancy test as enrollment * Documented HIV-1 infection * On nevirapine-containing ART for at least three months (ART group only) * CD4 cell count of greater than or equal to 350 (for non-ARV group only) * Currently sexually active and plans to stay sexually active for the next 6 months Exclusion Criteria: * Medical contraindications to COC use * Recent pregnancy (within 3 months) * Has breastfed in last 3 months * Last pregnancy was ectpoic * Has been sterilized * Has had any of the following conditions since last pregnancy, or since menarche if never pregnant: Pelvic Inflammatory disease Diagnosis of infertility * Has had DMPA within 6 months or NET injectable within 3 months of study entry (or has had no menses since last injection regardless of its timing) * has taken other hormonal therapies besides COCs (e.g., combined injectables, progestin implants or intrauterine systems, progestin-only contraceptive pills, medroxyprogesterone acetate, hormone replacement therapy) within 30 days of study entry * Has an acute infection or other opportunistic diseases requiring therapy within 14 days before enrollment * Has active drug or alcohol use that, in the opinion of the investigator, would interfere with adherence to study requirements * Has taken any prohibited medication within 30 days before study entry * Has chronic diarrhea, malabsorption or inability to maintain an adequate oral intake * Has any condition (social or medical) which in the opinion of the investigator would make study participation unsafe or complicate data interpretation