The reasons why newborns sleep with their mouths open usually include respiratory obstruction, nasal septum deviation and neonatal obesity, etc., which need to be treated as soon as they are found. Due to the newborn’s nasal cavity is small, when the baby due to cold, cold easily lead to increased nasal secretions, and then nasal obstruction, but also may cause nasal congestion; Secondly, when the newborn has a deviated nasal septum, because of the poor airflow can easily lead to insufficient supply of oxygen, so the newborn will be unconsciously sleep with his mouth open. In addition, some newborns after birth weight, and because of the newborn’s neck is shorter, so it is easy to lead to poor airflow and insufficient oxygen supply, occurs unconsciously open mouth sleep. Newborns sleeping with their mouths open may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.