PROJECT SUMMARY: HIV incidence doubles during pregnancy and postpartum period compared with non- pregnant women, underscoring the urgent need for prevention interventions tailored to high-risk pregnant and breastfeeding women. Incident maternal HIV infections lead to an estimated one-third of all infant HIV infections. South Africa expects over 76,000 infant HIV cases in the next decade; one-third of those can be prevented by eliminating maternal HIV acquisition. Pre-exposure prophylaxis (PrEP) in pregnancy and breastfeeding is safe and effective at preventing HIV. However, PrEP use remains low in pregnancy, and drops precipitously in the postpartum period. Our team is made up of experts in epidemiology, behavioral science, health economics and HIV prevention in pregnant women from University of California Los Angeles and the University of Cape Town. Together we have implemented one of the first studies to integrate PrEP into antenatal care in South Africa (“PrEP-PP”; R01MH116771). We propose to test a novel strategy to optimize PrEP in pregnant and postpartum women in South Africa. Our randomized control trial (RCT) is designed to address key barriers to maternal PrEP use and evaluate cost-effectiveness to inform national policy. This trial builds on our earlier work demonstrating the acceptability, feasibility, safety and potential efficacy of a package of interventions including PrEP, HIV self-testing (HIVST) for the participant and her partner(s), and enhanced adherence counseling (with bio-feedback on adherence) combined with home PrEP delivery for women who want to take PrEP but have difficulties adhering. We developed and piloted a novel intervention entitled, Stepped Care to Optimize PrEP Effectiveness in Pregnant and Postpartum women (SCOPE-PP) that addresses barriers to taking daily PrEP by reducing clinic visit frequency and empowering women to adhere to PrEP. We will evaluate SCOPE-PP in a pragmatic RCT of pregnant and postpartum women at risk of HIV acquisition. We will enroll 500 pregnant women in antenatal care and follow them through 12m postpartum. Women in the intervention will be offered: HIVST for participants & partners, rapid PrEP collection with enhanced adherence counseling. Women with poor PrEP adherence will be offered a differentiated care model of home PrEP delivery to de-link PrEP from clinical visits. The primary outcome is PrEP continuation and adherence in postpartum women, measured through drug levels of tenofovir diphosphate. We aim to: 1) Evaluate the efficacy of the SCOPE-PP intervention on PrEP adherence in pregnant and postpartum women in a RCT; 2) Assess the acceptability and feasibility of integrating SCOPE-PP into ante- and postnatal care using a consolidated framework for implementation research; and 3) Estimate the incremental cost effectiveness of SCOPE-PP vs. standard of care per HIV infection and disability-adjusted life-year averted. This research is critical to inform maternal PrEP interventions to ...