ABSTRACT This F31 proposal aims to evaluate pregnant and postpartum women’s preferences for different pre-exposure prophylaxis (PrEP) methods and identify early process indicators for implementing these options in maternal and child health (MCH) systems. HIV incidence remains unacceptability high among adolescent girls and young women (AGYW) in East and Southern Africa and evidence suggests a two-fold higher risk of HIV acquisition during pregnancy. Daily oral PrEP is scaling up for pregnant/postpartum women in Kenya but despite appreciable uptake of oral PrEP by pregnant/postpartum women, >50% discontinue within 30 days of initiation. Unique attributes of pregnancy and postpartum may influence discontinuation, including co-occurring side effects (e.g., nausea) and demands of motherhood. New long-acting (LA)-PrEP methods (e.g., vaginal rings and injectables) have recently been approved and may address some barriers to PrEP persistence during pregnancy/postpartum, though no systemic evaluation has been conducted to date. Early implementation studies for LA-PrEP can accelerate its integration into maternal and child health (MCH) systems. Kenya, as one of the first countries to implement PrEP at scale, is an ideal setting to study expanding access and uptake among pregnant women. This proposal leverages data collected in an ongoing RCT (MR01NR019220, MPI: Pintye, Kinuthia) among 600 Kenyan women who initiate daily oral PrEP during pregnancy and are followed through nine months postpartum. The study includes longitudinal assessments of preferences for PrEP methods (pills, vaginal rings, injectables). Interviews and focus-groups are also conducted among PrEP users, providers, and PrEP stakeholders to ascertain implementation outcomes. In Aim 1, we will determine pregnant and postpartum women’s preferred PrEP attributes for HIV prevention-effective use applying discrete choice experiment analysis methods to identify preferred PrEP method. In Aim 2, we will identify profiles of pregnant/postpartum women who would prefer novel PrEP methods using latent class models to identify distinct profiles of study participants with different preferences for several PrEP methods (daily oral, vaginal ring, injectable) and the driving predictors of preference within these classes. In Aim 3, we will evaluate implementation determinants for integration of LA-PrEP formulations into MCH systems using qualitative research informed by an implementation science process framework. The proposed research plan will provide the F31 candidate rigorous predoctoral training in 1) analytic techniques in discrete choice experiments and latent class modeling, 2) measurement of social and structural determinants of HIV risk for pregnant/postpartum women, and 3) application of a process framework for implementation of LA- PrEP. This study will be the first evaluation of user-preferences for new PrEP methods among pregnant and postpartum women and findings will help inform messaging and i...