UNICEF, WHO and the World Bank have collaborated to produce a set of joint estimates of child malnutrition for 2011 as well as trends since 1990. The report is available here. The inter-agency effort and collaboration ensured that the same underlying harmonized survey datasets and methodology were used to compute global and regional aggregated estimates as well as estimates by income groups. The aggregation methodology adopted represents current international best practice and is based on a linear mixed-effect modeling approach (see here for details). All the latest data on prevalence and numbers of child stunting, underweight, overweight and wasting are available from the WHO Global Database on Child Growth and Malnutrition and are incorporated in the World Bank’s World Development Indicators databank.