Infants spitting up blood are considered to be related to nipple rupture, thrush, abnormal blood clotting function, gastrointestinal bleeding and other factors. 1. Cracked nipple, babies spitting up blood may be in the process of eating milk nipple rupture, there is blood into, so the symptoms appear. 2. Thrush, if the baby has thrush, the mucous membrane is stimulated during the process of breastfeeding, which may lead to capillary rupture and bleeding, and therefore the symptoms of infant spitting up with blood will occur. 3. Abnormal coagulation function, if the baby has abnormal coagulation function, it may lead to bleeding in various parts of the body. 4. Gastrointestinal bleeding, if the baby has gastrointestinal bleeding, the gastrointestinal mucous membrane damage or tear may lead to this symptom. There may be other reasons for babies to spit up blood, so it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of the doctor.