Infancy refers to the period from 28 days to one year after birth, and the normal respiratory rate is about 30-40 times/min. If the respiratory rate increases, it may be caused by respiratory system diseases, or by extra-pulmonary diseases such as cardiovascular system and nervous system, and many diseases may cause shortness of breath. Common causes of shortness of breath in infants include: 1, respiratory system diseases such as upper respiratory tract infection, nasal congestion, acute laryngitis, fever, pneumonia, asthma, respiratory obstruction, etc.; 2, digestive system diseases such as diarrhea that cause dehydration or bloating that affect breathing can also cause shortness of breath; 3, circulatory system diseases such as congenital heart disease, myocarditis and other diseases that cause cardiac insufficiency and heart failure can also be accompanied by shortness of breath; 4, shortness of breath. 4, neurological diseases such as encephalitis, myasthenia gravis, myotonic dystrophy, metabolic acidosis and other diseases may also cause shortness of breath. There are many causes of shortness of breath, and the analysis of the causes needs to be judged according to the clinical symptoms. In short, the causes of shortness of breath are complex. If shortness of breath appears suddenly, we need to pay attention to the common causes such as fever, respiratory tract infection, nasal congestion, etc. If the cause of shortness of breath is unknown, we need detailed examination to clarify the cause and target treatment.