Infant spitting up may be related to physiological factors, digestive tract malformation, central nervous system infection and so on. 1. Physiological factors: infants’ stomach volume is small and horizontal, due to the cardia and the bottom of the stomach muscle tone is low, while the pyloric sphincter is better developed, so it is easy to occur pyloric spasm and spitting up. If the baby is fed too much milk, the baby eats milk too fast, the feeding position is not correct, and the baby is not burped up after feeding, etc., the baby will spit up after eating milk. 2. Gastrointestinal malformation: such as congenital pyloric obstruction, milk can not pass through the pylorus to enter the intestine, retention in the stomach, so that the baby bloating appears to spit up milk. 3. Central nervous system infections: the body is infected by pathogenic microorganisms, due to the imperfect development of the blood-brain barrier in newborns, causing meningitis, encephalitis, so that the intracranial pressure increases, which can cause macrosomia. There may be other reasons for babies to spit up, so it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy.