The baby spit up when burping may be caused by physiological factors such as feeding more milk, improper breastfeeding posture, or considered to be caused by gastroesophageal reflux, congenital hypertrophic pyloric stenosis and other diseases. 1. Physiological factors: more breastfeeding, improper breastfeeding posture, due to the presence of a large amount of air in the baby’s body, will lead to the baby spit up. 2. Gastroesophageal reflux: Gastroesophageal reflux may be caused by factors such as anti-reflux structures and reduced esophageal clearance. Affected children may experience reflux of gastric contents into the esophagus, which is manifested as spitting up when burping. 3. Congenital hypertrophic pyloric stenosis: The child will vomit and spit up milk when parents burp. Vomiting occurs soon after birth and is often progressive. There may be other reasons for babies to spit up when burping, so it is recommended to go to the hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of the doctor.