1. Reasons for babies to spit up milk 1.1 Dietary problems Three-month-old babies gradually begin to enter the complementary feeding period. If the diet is improper, overfeeding or feeding time is too short, it will lead to spitting up milk. 1.2 The digestion is not fully developed. The digestion of 3-month-old babies is not fully developed and can easily cause vomiting. At this time, attention should be paid to diet and feeding methods. 1.3 Incorrect posture During the feeding process, if the posture is incorrect, such as incorrect holding posture or incorrect head position,