mWACh-PrEP: A SMS-based Support Intervention to Enhance PrEP Adherence During Pregnancy and Breastfeeding

In high HIV prevalence regions, women are at high risk for HIV during pregnancy and breastfeeding. To protect women and reach elimination of mother-to-child HIV transmission, the World Health Organization recommends offering oral tenofovir (TFV)-based pre-exposure prophylaxis (PrEP) to HIV-negative pregnant and postpartum women in high-burden settings. Although most pregnant Kenyan women with HIV risk factors accept PrEP when offered, \>50% discontinue PrEP within 30 days of initiation and sub-optimal adherence is common. To date, no intervention studies to improve PrEP adherence include pregnant or postpartum women. The investigators adapted an SMS communication platform (mWACh) to send PrEP-tailored, theory-based SMS to facilitate adherence among pregnant women who initiate PrEP. In a non-randomized pilot, the investigators found that mWACh-PrEP recipients were more likely to persist with PrEP use and to self-report high adherence. The investigators propose a randomized trial to determine the effect of the mWACh-PrEP tool on PrEP adherence during pregnancy through the postpartum period. The investigators will also gather data on cost and delivery using the Proctor Implementation Outcomes Framework to expedite translation into routine practice. The overarching hypothesis is that mWACh-PrEP will improve PrEP adherence among mothers at-risk for HIV, be acceptable to patients and providers, and be cost-effective. The study will be executed via the following aims: Aim 1- To determine the effect of the mWACh-PrEP tool on PrEP adherence during pregnancy through the postpartum period among women who initiate PrEP within ANC-PrEP. We will conduct a 2-arm randomized trial comparing mWACh-PrEP vs standard of care (SOC, i.e. in-clinic adherence counseling) among HIV-uninfected pregnant women with high HIV acquisition risk (defined by validated risk score) who initiate PrEP. The primary outcome will be adherence at 6 months postpartum (TFV hair levels \>0.038 ng/mg; consisten