Why do babies spit up milk just after feeding? It is common for babies to spit up milk right after they finish feeding. In fact, spitting up is one of the normal reactions of babies. The main reason is that the baby\’s gastrointestinal function is not yet fully mature and the digestive capacity is limited. Moreover, the baby will inhale a large amount of air when swallowing when eating. At this time, the air and food will form foam, which will Stimulates the baby\’s pyloric sphincter, causing stomach contents to reflux and spit out from the mouth. Aspect 1: Dietary precautions: baby’s milk volume, feeding posture, and eating