This is a prospective, multicenter, observational study designed to evaluate the effectiveness and safety of Bictegravir/Emtricitabine/Tenofovir Alafenamide (B/F/TAF) in pregnant women living with HIV. Given the limited prospective data on B/F/TAF use during early pregnancy, this study aims to address the evidence gap by observing women who are on B/F/TAF for at least six months with sustained viral suppression (HIV RNA \<50 copies/mL) and are within the first trimester. Participants will continue B/F/TAF throughout pregnancy and up to 12 weeks postpartum per routine clinical practice. No experimental intervention will be assigned. The primary objective is to assess the proportion of participants achieving HIV RNA \<50 copies/mL at 12 12 weeks of pregnancy. Secondary objectives include maternal viral suppression at 28 weeks, delivery, and postpartum; safety and tolerability; maternal and neonatal outcomes including congenital anomalies, APGAR scores, infant HIV status, and growth parameters. The study will enroll at least 50 participants across five clinical centers in China. Findings will provide real-world evidence on the use of B/F/TAF as an alternative integrase inhibitor-based regimen for pregnant women with HIV.