Two months baby spit up sour milk, consider too much food, irritable bowel syndrome, gastrointestinal tract infection and other factors. 1. eating too much: baby gastrointestinal digestion itself is not good, one-time eating too much, resulting in gastrointestinal indigestion, food has been piled up in the intestinal tract, can not be discharged in a timely manner, spit out of the milk will have a clear acidic flavor. 2. Irritable bowel syndrome: Irritable bowel syndrome is not handled in a timely manner, may lead to gastrointestinal tract dysfunction, dysbiosis, not timely supplementation, will affect the gastrointestinal digestion, resulting in spit up of sour milk. 3. gastrointestinal tract infection: for example, infected bacteria, viruses and other microorganisms, pathogenic bacteria repeatedly stimulate the gastric mucosa, easy to affect gastrointestinal digestion, which leads to spitting acid. Two months of the baby spit up acid, may also be related to functional dyspepsia, functional constipation and other factors, purely based on the symptoms can not identify the cause, it is recommended to take the baby to the doctor in a timely manner, and through the digestive system to analyze the cause of the disease, and then standardized treatment.