The exceptions are Peru and the Plurinational State of Bolivia, where the drop in chronic undernutrition coincided with a rise in the relative differential by quintiles. Although chronic undernutrition (stunting) is found (on a much smaller scale) in the fifth quintile, the factors involved are probably biological or associated with specific diseases. In Mexico, the estimates available put the rate of chronic undernutrition among under-fives at 13.6% (Rivera-Dommarco and others, 2013). The analysis presented in this section is confined to countries in the region for which there is recent DHS information available. Methodologically, it is equivalent to the indices used later in this chapter to analyse inequalities in reproduction and in access to durable goods. The concentration curves, which show the accumulation of the variable analysed (in this case the prevalence of undemutrition) over the distribution, are above the equidistribution line for all countries, showing how undernutrition is concentrated among the poorest children (see annex figure II.A.6).