1, whether there is gastroesophageal reflux: small infants choking, choking, choking is an important cause of pneumonia, parents of affected children should be reasonable feeding, pay attention to the speed and rhythm of feeding, to avoid choking; at the same time sleep to take the head of the bed elevated 20-30 degrees of sleep position. 2, whether suffering from congenital heart disease: especially left-to-right shunt caused by increased pulmonary blood type of precordial disease has suffered from pneumonia. Physical examination as well as cardiac ultrasound examination can be clarified. 3, whether there are allergic factors: about 1 month after birth and later, children with a history of eczema on the face or body, a family history of allergies, and a family history of asthma are prone to pneumonia after infection and are accompanied by wheezing. 4. The presence of abnormal immune function: children born prematurely, with a family history, severe eczema, frequent diarrhea, and abnormal reactions to vaccines such as BCG vaccine, and those with abnormal blood picture are prone to recurrent pneumonia and need to be alerted to abnormal immune function. 5. Children with anemia are prone to pneumonia. 6. Developmental abnormalities or foreign bodies of the respiratory system: this cause should be considered in children with recurrent respiratory infections, unsatisfactory conventional treatment, combined with other developmental abnormalities or premature birth.