"The inverse equity hypothesis was based both on Tudor Hart’s inverse equity law and on Rogers’s theory of diffusion of innovations, according to which early adopters include families with greater access to information and to the resources required, in this case for institutional childbirth.

To test the inverse equity hypothesis, we analyzed the proportion of births occurring in a health facility by wealth quintile in 286 surveys from 89 low- and middle-income countries (1993–2015) and developed an inequality pattern index. Positive values indicate that inequality is driven by early adoption by the wealthy (top inequality), whereas negative values signal bottom inequality. We address 3 scenarios:

- First, when national coverage is low and top inequality prevails, governments should work to increase access in all groups. This situation is most common in low-income countries.

- Second,  When national coverage is high and bottom inequality is present, targeting makes sense. Such situations are more frequent in upper-middle–income countries.

- Third scenario refers to the introduction of new interventions by a government. These may be deployed in ways that will reduce or even invert the usual inequality gradients. For instance, Peru introduced Haemophilus influenzae type b vaccine in 1998 in high-mortality, low-income districts; the vaccine was only introduced in the more developed areas of the country in 2004, by when high coverage had already been achieved in the districts that were targeted initially" (VICTORA et al., 2018).

Read more: American Journal of Public Health