On Mar. 9, 2020, among African adolescent girls and young women who took HIV pre-exposure prophylaxis (PrEP) daily, levels of the PrEP drug tenofovir were more than 30% lower in those who were pregnant than in those who had recently given birth. All 40 study participants took PrEP under direct observation, confirming their near-perfect adherence. PrEP drug levels were lower to a similar degree in the pregnant African adolescent girls and young women compared to American men and non-pregnant, non-lactating women who took PrEP daily under direct observation in an earlier study.<./p>