Baby five months, three days a pull back may be a normal phenomenon, such as digestive function enhancement, intake is too small, etc., but there may be abnormal phenomena, such as constipation. 1. digestive function enhancement: five months after the baby’s digestive system continues to improve, the digestive enzymes in the gastrointestinal tract will also increase, and digestive function enhancement, which leads to the baby produce less food residue, the phenomenon of three days pull back. 2. too little intake: if the baby’s meal size is small, less intake of breast milk or milk powder, can also be due to the intestinal food residue is less, and the phenomenon of three days pull back. 3. constipation: constipation can also lead to five months baby three days pull back, and feces hard not easy to discharge, when serious, can damage the mucosa of the anus, triggering anal fissure. The baby five months, three days to pull back may also have other reasons, it is recommended to go to the hospital, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.