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. 2025 Nov 15.
doi: 10.1007/s10461-025-04952-z. Online ahead of print.

Adherence to Oral HIV Pre-exposure Prophylaxis During Pregnancy and the Post-partum Period: Lessons Learned in an Open-Labelled Clinical Trial

Nondumiso Khoza  1 , Alicia C Desmond  2 , Dhayendre Moodley  3   4
Affiliations

Adherence to Oral HIV Pre-exposure Prophylaxis During Pregnancy and the Post-partum Period: Lessons Learned in an Open-Labelled Clinical Trial

Nondumiso Khoza et al. AIDS Behav. .

Abstract

Self-reports and returned pill count as measures of adherence to the daily oral HIV preexposure prophylaxis (PrEP) regimen in clinical trials have led to misleading outcomes. There is limited adherence data for pregnant and breastfeeding women who initiated daily oral PrEP in clinical trials. In an open-label PrEP clinical trial, adherence to daily oral tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) was measured using returned pill counts during pregnancy and post-delivery, up to 54 weeks. Intracellular tenofovir diphosphate (TFV-DP) was measured in stored dried blood spot (DBS) twice during pregnancy and at 6, 26, and 54 weeks post-delivery. True adherence was estimated based on TFV-DP levels corresponding to the number of doses taken per week. Of 271 women, 244 (90.0%), 116 (42.8%), and 84 (31.0%) received PrEP during pregnancy, or until 26 or 54 weeks post-delivery, respectively. Based on pill counts, 80-95% of women took > 80% of the dispensed PrEP pills during pregnancy and postpartum. TFV-DP was undetectable in 13.8-32.9% of women during pregnancy, and 32.9-40.5% of women postpartum. Furthermore, only 21.6% and < 10% of women had TFV-DP levels equivalent to 7 doses/week during pregnancy and postpartum, respectively. Real-time pill count data overestimated adherence to a daily oral PrEP regimen among pregnant and postpartum women. Based on TFV-DP levels, only 20% of pregnant women and 10% of postpartum women had levels suggestive of adherence greater than 80%. Lack of transparency in adherence disclosure underscores the need for real-time, objective measures of adherence to inform targeted adherence counseling.Clinical Trial Number CAP016 is on ClinicalTrials.gov ( https://clinicaltrials.gov/ct2/show/NCT03227731 ).

Keywords: Adherence; Postpartum; Pre-exposure prophylaxis; Pregnancy; Tenofovir diphosphate; Tenofovir disoproxil fumarate.

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Conflict of interest statement

Declarations. Conflict of interest: The authors have no relevant financial or non-financial interests to disclose. Research Involving Human and Animal Participants: The parent study (CAP 016) was conducted in compliance with approval from the South African Health Products Regulatory Authorities (SAHPRA). This study was approved by the University of KwaZulu-Natal Biomedical Research Ethics Committee (BREC/00003767/2022). Informed Consent: All participants signed an informed consent that included study follow-up procedures and storage of specimens for future research. All laboratory specimens, evaluation forms, reports, and other records were identified only by a coded number to maintain subject confidentiality.

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