The authors obtained data about hemoglobin and anemia for children and women of childbearing age from the population-representative data sources of 107 countries. They found that children's and women's hemoglobin statuses improved in some regions where concentrations had been low in the 1990s, leading to a modest global increase in mean hemoglobin and a reduction in anemia prevalence, from 33% to 29% and 43% to 38% in non-pregnant and pregnant women (respectively), and from 47% to 43% in children. This translates to around 801 million women and children with anemia in 2011.
Stevens, Gretchen A, Mariel M Finucane, Luz Maria De-Regil, Christopher J Paciorek, Seth R Flaxman, Francesco Branca, Juan Pablo Peña-Rosas, Zulfiqar A Bhutta, and Majid Ezzati. "Global, Regional, and National Trends in Haemoglobin Concentration and Prevalence of Total and Severe Anaemia in Children and Pregnant and Non-pregnant Women for 1995–2011: A Systematic Analysis of Population-representative Data." The Lancet Global Health 1, no. 1 (2013): E16-25.