Protease Inhibitors and Combined Oral Contraceptive Pharmacokinetics and Pharmacodynamics

Inclusion Criteria: * HIV positive * Female * Age 18-45 * Using any of the following medication regimens: no ARV medication, entry inhibitors, nucleoside reverse transcriptase inhibitors (NRTIs), integrase inhibitors, and CCR5 agonists. Acceptable NRTI combinations include zidovudine (ZDV), lamivudine (3TC), emtricitabine (FTC), didanosine (ddl), stavudine (d4T), abacavir (ABC), and tenofovir disoproxil fumarate (TDF) * Ovulatory (mid-luteal progesterone \>3ng/dL) * Not planning to conceive during the study period * Willing to abstain from grapefruit products * If taking ritonavir, willing to use alternate non-hormonal contraception * BMI \< or = 40 * Able to consent in English or Spanish * No change in medication regimen for at least 21 days prior to study entry and no planned change during the study period * CD4 \> or =200, and/or not considered profoundly immuncompromised by primary HIV provider Exclusion Criteria: * Using on the combination of ZDV at d4T * Platelets \<50,000 * AST or ALT \> twice upper limit of normal * Bilirubin \> twice upper limit of normal * Use of other CYP3A4 inducing or inhibiting medications * Pregnant or breastfeeding in last 30 days * Use of DepoProvera in last 180 days * Use of any other hormonal contraception in last 30 days * Undiagnosed vaginal bleeding or invasive cancer of the reproductive tract -\>50% change in tobacco use in the last month * Initiation or titration of methadone therapy in the last month * Uncontrolled thyroid disease * Contraindication to estrogen use * Inability to comply with study protocol