Transgender women (TW) who are living with HIV can join this study to see if taking estradiol, a form of estrogen for feminizing hormone therapy (FHT), affects their HIV medication, called antiretroviral therapy (ART). The trial lasts for 48 weeks, where participants will take study-provided estradiol and continue their regular HIV medication. The study also wants to find out if different doses of estradiol affect the ART's effectiveness. Participants will have regular visits to check their medication levels and health.

• The study lasts 48 weeks with regular visits.
• Participants receive free estradiol for the study period.
• Participants must already be taking HIV medication.

To join, you must be at least 18 years old, identify as a transgender woman, female, or transfeminine, and have stable HIV treatment. You should not have certain health issues like liver problems or clotting disorders. Participants must avoid using any hormone therapy not provided by the study during this time. The study will help understand how HIV medication and hormone therapy can work together safely.