The causes of upper respiratory tract infections in two-month-old children include the following: First, they are caused by children getting cold. If children wear too little clothes or sweat too much in the cold winter, these causes can cause upper respiratory tract infections in children, resulting in nasal congestion, runny nose, sneezing and other symptoms. Secondly, upper respiratory tract infections caused by cross infection. If parents or other people in close contact with children have upper respiratory tract infections, they can cause upper respiratory tract infections in children through cross-infection. The above two ways are the most common conditions that cause upper respiratory tract infections in children.