Spitting up is a common phenomenon in infants and has two main causes: first, the physiological anatomy of the gastrointestinal tract unique to infants tends to cause spitting up; second, it is a symptom of gastrointestinal or systemic diseases. In general, the former is more common. When milk enters the stomach, the pancreatic contraction is weaker than the pylorus, leading to reflux of milk from the stomach back to the esophagus, and when the baby lies down directly after feeding, it is more likely to cause vomiting. In addition, incorrect breastfeeding posture, anxious breastfeeding and excessive air inhalation can also easily cause spitting up. This is a common physiological overflow, is a normal physiological phenomenon, parents do not need to be too nervous, it is recommended that when breastfeeding, articulate the nipple, avoid excessive air inhalation, after nursing vertical hold pat back, burping and then lying flat or lying on the side. When babies suffer from neonatal pneumonia, they may also spit up milk. In addition, gastrointestinal diseases such as congenital pyloric stenosis or hypertrophy can also cause vomiting, which occurs after eating. In the case of pathological vomiting, the infant will also have other manifestations such as mental weakness and abdominal discomfort, so parents should pay attention to the infant and seek timely medical attention.