A three-year-old two-month-old baby coughing during the day and at night may be caused by respiratory tract infections, airway allergies, or a foreign body in the airway. 1. When babies suffer from respiratory tract infections, such as upper respiratory tract infections, bronchitis, bronchopneumonia, etc., there will be symptoms of coughing during the day and at night, and some babies may be accompanied by nasal congestion, runny nose, fever and other symptoms. 2. If the baby is allergic, after exposure to allergens, there will be symptoms of coughing and wheezing during the day and at night, and some babies may be accompanied by nasal congestion, runny nose and sneezing. 3. If the baby inadvertently causes the airway to inhale foreign objects or choke on food, it will also cause the baby to develop coughing symptoms during the day and at night, and some babies may be accompanied by respiratory difficulties, wheezing and other symptoms. When your baby develops a cough both during the day and at night, take your baby to the pediatrician at the hospital in time to avoid delay in treatment.