The most common cause of nosebleeds in 1 year old babies is due to the dry environment, as the dry environment and reduced humidity will lead to increased brittleness of the nasal mucosa blood vessels, which can easily lead to nosebleeds. Nosebleeds in babies may also be related to infection. After the upper respiratory tract infection, the nasal cavity will host bacteria, which will destroy the nasal mucosa and cause bleeding. Individual babies with nosebleeds may also be suffering from blood system disorders and should be brought to the hospital for blood tests to check if there is a reduction in platelets and other conditions.