Anaemia means the blood has too little haemoglobin, the protein in red blood cells that carries oxygen around the body. It commonly causes tiredness, dizziness, headaches and shortness of breath, and in pregnancy is linked to premature birth, low birth weight and maternal death. In young children, severe anaemia can hold back cognitive and motor development, with knock-on effects on schooling and, later, on earnings. WHO estimates that about 605 million women aged 15–49 had anaemia in 2023, and its latest estimate for children, from 2019, is 269 million children aged 6–59 months.
Anaemia has many causes. Iron deficiency, mostly from diets low in absorbable iron, is the most common nutritional cause, but infections such as malaria, hookworm and schistosomiasis, tuberculosis and HIV, inherited blood disorders such as sickle cell disease and thalassaemia, heavy menstrual bleeding and blood loss in childbirth also play a large part. The burden is heaviest in low- and lower-middle-income countries, especially in South-East Asia and Africa, and among women and children in rural areas, poorer households and families with no formal education. Because so many factors are involved, programmes that rely on iron alone have not been enough to bring rates down.