Drug Concentrations in Hair and Dried Blood Spots as Preexposure Prophylaxis Adherence Metrics During Pregnancy and Postpartum.

We evaluated hair tenofovir (TFV) concentrations as an adherence metric for HIV preexposure prophylaxis during pregnancy and postpartum and compared hair levels with TFV-diphosphate levels in dried blood spots (DBSs). Overall 152 hair samples from 102 women and 36 hair-DBS paired samples from 29 women were collected from a subset of women in a cluster-randomized trial. Having a partner with HIV was associated with higher hair TFV levels (P < .001). Hair TFV concentrations were strongly correlated with DBS TFV-diphosphate levels (r = 0.76, P < .001), indicating hair as a promising cumulative adherence metric for perinatal preexposure prophylaxis assessment.