In general, the normal value of transcutaneous oxygen saturation is >95% in newborns with normal growth and development. Oxygen saturation is the concentration of oxygenated hemoglobin in the blood. The oxygenation of the lungs and the oxygen-carrying and oxygen-transporting capacity of hemoglobin can be estimated by monitoring arterial oxygen saturation. Normal newborns have a transcutaneous oxygen saturation value of >95%. Cyanosis occurs when oxygen saturation decreases and is caused by an increase in reduced hemoglobin in the blood above a certain level. It is generally accepted that bruising of the face and trunk of the newborn can be detected by the naked eye when the arterial blood reduced hemoglobin level is >50 g/L, and bruising of the oral cavity and tongue mucosa can also be seen when the reduced hemoglobin is >30 g/L. The causes include physiological and pathologic cyanosis, and pathologic cyanosis can be seen in heart failure, shock, neonatal asphyxia, congenital malformation of the respiratory tract, pneumonia, pneumothorax, transposition of the great arteries and other diseases. When a child has a decrease in oxygen saturation, it is necessary to consult a doctor in time to determine the cause of the disease and then under the guidance of the doctor for treatment.