The reason why the monthly baby spit up may be caused by the baby’s own physiological reasons, but also may be caused by improper feeding, disease factors. 1. Physiological reasons: the baby was just born, the development of the digestive system is not perfect, the stomach was horizontal structure, and the stomach capacity is small, the pancreatic sphincter relaxation, the intake of milk a little more than the phenomenon of spitting up, this situation will gradually reduce with the development of the baby. 2. Improper feeding: feeding posture is not right, or feeding too fast or feeding too much milk at a time, more than the baby’s normal stomach capacity, may lead to baby spitting up. 3. Disease factors: babies with gastrointestinal infections, respiratory infections, intestinal obstruction, intussusception and other diseases, may appear baby spit up. There are many reasons for babies to spit up, if the spitting up is too frequent, or accompanied by more than crying, etc., you need to consult a doctor in time.