Newborns always sleep with their mouths open can be seen in normal physiological phenomena, pathological conditions (such as neonatal pneumonia), whether normal, according to the baby’s specific judgment, such as neonatal pneumonia respiratory distress caused by the baby’s mouth open breathing, is not normal. 1. Physiological phenomenon: the newborn’s nasal cavity is narrow, the nasal mucosa is tender, easy to be affected by external factors, such as sleeping in a low ambient temperature, nasal congestion can occur, and then the baby can be manifested as “always sleep with his mouth open”, this kind of babies usually do not have obvious symptoms of abnormal discomfort. 2. Pathological conditions: such as neonatal pneumonia, can be caused by viral or bacterial infections and other pathogens, the baby can appear fever, moaning or spitting, severe cases can appear shortness of breath and other respiratory distress manifestations, in the sleep of the phenomenon of open-mouthed breathing, the examination can be detected in the lungs of the fine dampness of the rales, chest X-ray examination can assist in the diagnosis of this kind of situation is abnormal, need to be actively consulted for treatment. It is recommended that the newborn be evaluated by a specialist if necessary to determine whether the condition is normal.