1. Common reasons why babies spit up milk: Babies spitting up milk is a problem that many new parents often encounter. In fact, it has many different reasons. Here are some common reasons: 1. Incorrect feeding posture: If the feeding posture is incorrect, it will cause the baby to swallow too much air, causing vomiting. 2. Overfeeding: If you feed your baby too much or too frequently, it will cause excessive digestive burden and cause vomiting. 3. Acid reflux: Acid reflux refers to the backflow of stomach acid into the esophagus and mouth