Modeling the Potential Impact of Mentor Mother Programs on Vertical Transmission of HIV in Kenya.

Background: Peer support provided by "mentor mothers" (MM) may increase retention in care for pregnant and breastfeeding women (PBFW) living with HIV, which can lead to improved viral suppression and prevention of vertical transmission (PVT). The impact of MM on PVT may differ among PBFW subpopulations with different baseline risks of antiretroviral therapy (ART) interruption.

Method: We used a microsimulation model of HIV progression and care for PBFW living with recently acquired HIV in Kenya to evaluate an MM program that reduced the cumulative risk of ART interruption between initiation of antenatal care and 18 months of postpartum breastfeeding by 40%. We conducted this evaluation in 2 maternal populations: (1) newly positive (NP) pregnant women who initiate ART during antenatal care and are at greater risk of ART interruption and (2) known positive (KP) women who initiate ART prior to conception. We simulated live births, maternal deaths, and vertical transmission with and without MM services to determine the impact of MM.

Results: In the absence of MM services, infants acquired HIV at a rate of 609 vs. 459 per 10,000 live births in the NP vs. KP populations. MM services reduced vertical transmission by 15.1% among NP women, compared to a 6.5% reduction among KP women.

Conclusions: MM services can reduce vertical transmission among PBFW living with HIV, with greater potential for PVT among NP women compared to KP women. More research evaluating MM programs in these 2 maternal populations will help refine estimates of their PVT impact.