1. The main reasons for babies spitting up milk 1.1 Underdeveloped digestion 1.2 Incorrect feeding methods 1.3 Overeating in babies 1.4 Spitting up caused by infection or disease 2. Infants spitting up milk due to incomplete digestion 2.1 Babies have small stomach capacity and are easy to fill up 2.2 Gastrointestinal tract Unstable peristaltic function 2.3 Insufficient gastric acid secretion 3. Incorrect feeding methods can also cause the baby to vomit milk 3.1 Incorrect feeding posture 3.2 The size and shape of the nipple are not suitable for the baby\’s mouth 3.3 The feeding time interval is too short or too long 4. The baby is too old