Level 1: Why do babies often spit up milk? After a baby is born, his or her digestion is not fully developed, so spitting up is easy. In addition, babies who eat too much, eat too quickly, or have incorrect posture can also cause spitting up. Another condition is reflux esophagitis, in which stomach acid backflows into the esophagus, irritating the esophageal wall and causing vomiting. Level 2: How to prevent babies from spitting up milk frequently? First of all, maintain appropriate feeding amount and frequency, and do not let your baby be overly full or hungry. Secondly, pay attention to the feeding posture, so that the baby\’s head is slightly higher than the body to prevent gastric juice reflux.