Forty-day-old babies spit up after eating milk can be seen in physiological phenomena, pathological conditions (such as congenital hypertrophic pyloric stenosis), intervention needs to be based on the reasons for the decision, such as improper feeding needs to be adjusted feeding methods. 1. Physiological phenomenon: for forty-day-old babies, the digestive tract is immature, the gastroesophageal sphincter is weak, the stomach is horizontal, easy to spit up, coupled with improper feeding in the process of feeding, such as feeding a large amount of food, feeding too fast or eating more air, the above phenomenon can occur. For such babies need to adjust the feeding method, such as pay attention to the feeding speed, after breastfeeding can be appropriate for burping, with the age of the above phenomenon can gradually disappear. 2. Pathologic conditions: (1) gastrointestinal dysfunction: if the baby eats more milk, the digestive tract can not tolerate, the above phenomenon may occur, may be accompanied by abdominal distension, abdominal discomfort and other manifestations. Such babies need to reduce the amount of feeding as appropriate, oral probiotics (such as bacillus subtilis bifidus granules) and other drugs under the guidance of a physician, if necessary, gastrointestinal decompression and other treatments. (2) Congenital hypertrophic pyloric stenosis: it is a kind of digestive malformation, vomiting is the first symptom, and the vomit can be milk or milk clot, and in severe cases, dehydration and electrolyte disorder can occur. The treatment for this type of baby is pyloromyotomy when the diagnosis is clear. It is recommended that babies who vomit after breastfeeding be seen by a specialist for evaluation and treatment.