Spitting up is usually caused by physiological factors such as immature stomach development and pathological factors such as gastrointestinal diseases. 1. Physiological factors: the immaturity of the baby’s throat and stomach, the looseness of the cardia, the closure of the cardia, and improper feeding, such as incorrect breastfeeding posture or overfeeding may cause the baby to spit up. 2. Pathological factors: the baby’s resistance is relatively low, easily affected by the external environment, disease, viruses, bacteria and even food, resulting in gastrointestinal diseases or respiratory tract infections, which can lead to spitting up of the baby. Little baby spit up may also have other reasons, it is recommended to go to the hospital in time, complete the examination to clarify the cause, under the guidance of the doctor to give targeted treatment or treatment.