Use of tenofovir-based PrEP among pregnant women in South Africa.

Objective: We developed Healthy Families-PrEP to support perinatal women to use HIV prevention strategies.

Design: Single arm study to evaluate PrEP use among pregnant women exposed to the intervention.

Methods: We offered safer conception counselling including TDF/FTC as PrEP with adherence support (Healthy Families-PrEP) for women planning for pregnancy in South Africa with a partner with HIV or unknown serostatus. Women completed pregnancy and HIV testing quarterly and were followed for one year or until pregnancy end. For those initiating PrEP, electronic pillcap data and plasma were collected. We described PrEP adherence by proportion of days with pillcap openings and proportion of women with detected (≥10ng/mL) plasma tenofovir.

Results: From November 2017 to January 2020, 326 women with median age 24 (IQR: 22-27) years enrolled. Partner HIV-serostatus was unknown by 316 (97%). Over 3,204 person-months of follow-up, 56 women became pregnant. Twenty-six women used PrEP during pregnancy and opened pillcaps on a mean of 53.1% (95% CI 46.9-59.3%) of days. Plasma tenofovir was detected among 25.0%, 15.4%, and 12.5% of women providing samples during months 0-3, 4-6, and 7-9. No HIV seroconversions were observed.

Conclusions: We observed low pregnancy incidence. Counselling may have encouraged delayed pregnancy plans; some women may have exaggerated pregnancy plans to enroll. About half of pregnant women used PrEP and took over half of doses by pillcap. Fewer than 25% had tenofovir detected, likely reflecting pregnancy-related pharmacokinetics and adherence challenges. High interest in pregnancy PrEP use highlights the need to optimize adherence support and prevention choice.