When the blood has insufficient red cells, or the red cells carry insufficient haemoglobin to deliver adequate oxygen to the tissues, this is called anaemia. There is normally a reduction in the haemoglobin concentrations in the mother's blood during pregnancy, and this allows a better blood flow around the womb (uterus) and to the baby. This is sometime called physiological anaemia and needs no treatment. True anaemia, however, can be mild, moderate or severe and can cause weakness, tiredness and dizziness. Severe anaemia makes women at risk of cardiac failure and is very common in low-income countries Anaemia has many causes including a shortage or iron, folic acid or vitamin B12. These are all required for making red cells and are available in a good diet. Iron shortage, however, is the most common cause of anaemia during pregnancy. Iron treatment can be given by mouth (oral), by injection into the muscle (intramuscular) or injection into the vein (intravenous). Blood transfusion or giving something which stimulates the body to produce more red cells (erythropoietin) are also possible treatments.