Infants who vomit after eating milk may be related to physiological causes such as improper feeding or pathological causes such as pyloric stenosis and esophageal atresia. 1. Physiological reasons: Since the stomach content of babies is relatively small, if the amount of breastfeeding is large or the interval between two feedings is too short, it can cause babies to spit up after eating milk. 2. Pathological causes: If the baby has pyloric stenosis, a disease that causes high hypertrophy and hyperplasia of the pyloric sphincter muscle due to congenital malformations and other reasons, causing obstacles to the passage of food and gastric juices, it may lead to spitting up after eating milk; after the birth of a child with esophageal atresia, violent choking and coughing will occur during the first feeding, and the milk will then spill out of the mouth and nostrils. It is recommended that infants who spit up after eating milk should go to the hospital in time to clarify the cause, and if treatment is needed, it should be standardized under the guidance of a doctor.