Lopinavir-ritonavir is a human immunodeficiency virus 1 (HIV-1) protease inhibitor boosted by ritonavir, a cytochrome p450 inhibitor. A warning about its tolerance in premature newborns was recently released, and transient elevation of 17-hydroxyprogesterone (17OHP) was noted in 2 newborns treated with lopinavir-ritonavir in France.