Four-month-old babies spitting up may be a normal physiological phenomenon, or it may be a symptom caused by disease. 1. physiological phenomenon: due to the baby’s age, the development of all body functions is not perfect, the situation of spitting up is mainly related to the swallowing function, gastrointestinal development, the baby ate the milk too fast may also cause spitting up, this kind of situation is usually a normal physiological phenomenon, the parents can be improved by the baby burp, give the baby attention to feed the baby to keep warm, to avoid the baby from being cold. 2. Diseases (1) Acute gastroenteritis: four-month-old babies spitting up can also be caused by acute gastroenteritis, the baby will appear nausea, vomiting, diarrhea and other adverse symptoms, there may also be fever. (2) Gastroesophageal reflux: it can cause babies to spit up frequently, and there will also be vomiting, acid reflux and other adverse symptoms, and some babies will experience shortness of breath. When the spitting up of four-month-old babies is more serious, they need to consult a doctor in time for examination and choose the appropriate treatment according to the doctor’s advice.