Anaemia is a blood condition that can make a person feel tired all the time. The blood contains red cells which carry oxygen around the body, delivering it to the muscles and organs where they use it to make energy. The most common cause of anaemia is shortage of iron in the diet. Anaemia causes problems in pregnancy and birth but it can be prevented by eating enough foods with protein and iron in them. Pregnant women need a lot of iron so they are routinely given iron tablets.