The baby did not poop for two days may be physiological reasons; if persistent may be constipation, food allergies and so on. Need to be analyzed specifically. 1. Physiological factors: the baby’s stomach capacity is small, may intake of food is relatively small, if the child did not cry excessively, eat normally, weight gain is normal, it is a normal phenomenon. 2. Constipation: it is a common cause of defecation disorders in children, mostly related to genetics, dietary habits, metabolism, anatomy and other factors, manifested as a decrease in the number of bowel movements or hard feces, difficult to discharge. There is pain in the anus during defecation. Sometimes a small amount of blood or mucus is attached to the surface of the fecal mass. Long-term constipation will be accompanied by dizziness, fatigue, lack of appetite, irritability, bitter mouth odor, mouth ulcers, sleep disturbance and other discomforts. 3. food allergy: baby two days no poop may also be due to food allergies, the onset of the age of infants and complication of eczema, wheezing bronchitis children, should be considered and milk or other food allergies, such as breastfeeding mothers to avoid milk, eggs, wheat, soy, fish, shrimp, shellfish seafood and other foods, may be able to make the baby defecation is relieved. There are many other reasons why the baby did not poop for two days, it is recommended to consult the doctor in a timely manner, by the specialist sound judgment assessment, and improve the relevant examination, give targeted treatment or treatment.