Four-month-old babies start formula breastfeeding mixed, the baby began four or five days to pull back, if there is no abdominal distension, vomiting, crying and other obvious discomfort manifestations, consider with the milk powder caused by the gastrointestinal tract peristalsis slowdown, but also may be associated with the baby’s gastrointestinal dysfunction. Milk powder inside no crude fiber, containing calcium element is relatively high, easy to cause constipation. Secondly, 4 months baby gastrointestinal tract is not yet developed, easy to intestinal flora imbalance, resulting in weakened digestive ability, thus constipation. Parents should pay attention to the baby’s milk powder, not too sticky, to avoid increasing the burden on the gastrointestinal tract, to alleviate the constipation, usually give the baby more water. Can also be under the guidance of the doctor, oral bifidobacteria and other intestinal probiotics to regulate. Four-month-old babies start formula breastfeeding mixed, the baby began four or five days to pull back, there may also be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.