Newborns spitting up in their sleep may be due to physiological factors such as imperfect development of the digestive system, or pathologic factors such as gastroesophageal reflux. 1. Physiological factors. Due to the imperfect development of the newborn’s digestive system, the esophageal sphincter and the immature development of the stomach muscles, the food in the stomach can not be completely controlled, just after eating milk, lying down to sleep, the phenomenon of spitting up will occur. The child is too fast in eating milk, too much, the breastfeeding posture is not correct, resulting in a large amount of air into the body when the child is eating milk, and reflux occurs when sleeping, so that the phenomenon of spitting up occurs. 2. Pathologic factors. It may be caused by gastroesophageal reflux, respiratory tract infection, rhinitis and other diseases. (1) Gastroesophageal reflux. When the child suffers from gastroesophageal reflux, the food refluxes into the esophagus during sleep, causing irritation to the esophagus, resulting in spitting up, coughing and other symptoms. (2) Respiratory tract infection. Respiratory infections are caused by viruses, bacterial infections, rain, etc., resulting in nasal congestion, headache, sore throat, vomiting and other symptoms that cause spitting up. (3) Rhinitis. A child with rhinitis will have symptoms such as nasal congestion, leading to feeding difficulties and spitting up, which is more likely to occur when the child is sleeping. Newborns spit up in their sleep, there may be 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.