There are many reasons why two-year-old babies often have fever at night, the more common ones may be caused by acute upper respiratory tract infection, tuberculosis or tonsillitis. 1. acute upper respiratory tract infection: some babies have acute upper respiratory tract infection, in the daytime there may be no obvious symptoms, to the night may appear fever, accompanied by cough, nasal congestion and other symptoms. 2. Tuberculosis: tuberculosis is a chronic infectious disease caused by infection with Mycobacterium tuberculosis, which can cause fever, night sweats, fatigue and other systemic symptoms. 3. Tonsillitis: babies with inflamed tonsils are also prone to fever at night, which may be accompanied by severe sore throat, headache, poor appetite and so on. Two-year-old baby often night fever may also have other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.