Many medical conditions cause anemia. Common causes of anemia include the following:
External bleeding: Loss of blood through heavy menstrual bleeding, wounds, as well as stomach ulcers can cause anemia.
Iron deficiency: The bone marrow needs iron to make red blood cells.
Anemia of chronic disease: Any long-term medical condition can lead to anemia.
Pregnancy: Water weight gain during pregnancy dilutes the red blood cells.
Poor nutrition: Vitamins and minerals are required to make red blood cells.
Alcoholism: Poor nutrition and lack of vitamins and minerals are associated with alcoholism.