• child health
• epidemiology
• public health
• AIDS

The sex gap in early-age death is one of the most important sources of child inequality in all societies, and it carries negative social consequences in the long run. In the absence of gender discrimination in the allocation of foods and heath resources, mortality rates are higher in boys than in girls.1–3 Recent studies however suggest that in sub-Saharan Africa, the general improvement in state capacity and the quality of political and democratic institutions has had stronger health benefits for boys, reducing the male-female gap in early-age mortality.4 5 Democratic indicators such as political participation, competitiveness in the recruitment of the executive and constraints on executive power substantially improved after 1990. These positive developments led to an improvement in the quality of public health institutions. Mabeu and Pongou’s research implies that the health benefits of these positive institutional changes have mostly accrued to boys, in part because these changes have helped constrain the negative influences of the male biological make-up on mortality.5 But this pattern was likely to be specific to HIV-unexposed children. Among HIV-exposed children, it seems that other forces were at play.

In this editorial, we analyse trends in the sex gap in neonatal death—death occurring within 1 month of birth-during the era of the AIDS epidemic, and argue that they were sensitive to the availability of antiretroviral medicines. Child exposure to HIV (during pregnancy, delivery and breast feeding) reduced the female survival advantage, but this situation was gradually reversed by the availability of antiretroviral treatment. Our argument is partly captured in figure 1, which shows unadjusted trends in the probability of neonatal death over the period 1960–2017 for both boys and girls in sub-Saharan Africa. Neonatal mortality declined substantially over this period for both sexes. However, as figure 2 shows, the decline was …