Haemophilia can be diagnosed before, during or after birth if there's a family history of the condition. A variety of specialist tests are carried out on blood to make the diagnosis - these test for the level and function of clotting factors or platelets.
If there's no family history of haemophilia, it's usually only diagnosed when a child begins to walk or crawl. They may experience joint bleeds or easy bruising.
Mild haemophilia may only be discovered later, usually after an injury or a dental or surgical procedure.