The importance of the first 1,000 days: An epidemiological perspective

According to current estimates, 23% of the world’s children under 5 years of age are stunted, a condition that is measured using short height-for-age (see Box 1.1) [1]. Although this represents a decline from 33% in 2000, the fact that 156 million children globally still suffer from chronic undernutrition underscores the continued need for renewed efforts and innovative approaches for growth promotion. Progress has been particularly slow in Africa, where one out of every three children is stunted (Figure 1.1) [1]. In fact, despite a decline in stunting prevalence, the absolute number of stunted children in Africa increased from 50.4 million in 2000 to 58.5 million in 2015 [1]. Although Asia has seen an average annual decline in the prevalence of child stunting of about 1.5%, from 38% in 2000 to 24% in 2015, countries in East Asia have accounted for most of this progress [1]. Reductions have been much slower among countries in South Asia where more than one out of every three children under age 5 is stunted. At a subregional level, more than 30% of children under 5 in Western Africa, Middle Africa, Eastern Africa, Southern Asia, and Oceania are stunted [1]. In addition to these geographical differences, there are also drastic sociodemographic disparities in the prevalence of chronic undernutrition. An 4analysis of 79 population-based surveys has illustrated that the prevalence of stunting is, on average, 2.5 times higher among children living in the poorest quintile of households than the richest quintile [1]. Similarly, the child stunting prevalence is 1.45 times higher in rural versus urban areas [2].