Iron-deficiency anaemia is usually caused by heavy bleeding, eg from an injury or after an operation. A common cause in women is heavy periods. You're more likely to develop it if you:take aspirin or other non-steroidal anti-inflammatory drugs(NSAIDs) as these can cause stomach bleeding; have problems with your digestive system that lead to bleeding in your stomach or bowel; if you don't get enough iron in your diet, or if the iron isn't absorbed properly. Surgery on your stomach or small bowel can also affect your absorption of iron. Women commonly develop iron-deficiency anaemia during pregnancy because their unborn baby needs iron and takes its supply from its mother. Children and toddlers may develop iron-deficiency anaemia because growth spurts take up extra iron.
Attribution: BUPA