Five-month-old babies have smelly stools, usually associated with improper feeding, gastrointestinal dysfunction, gastrointestinal infections and so on. 1. Improper feeding: the baby’s gastrointestinal digestive function is not perfect, if the feeding is not appropriate, for example, let the baby intake of too much protein, high-fat and high-sugar food, will make the food in the digestive tract can not be fully digested and decomposition, and the metabolites of the undecomposed increase, which will lead to the baby’s stool is very smelly. 2. Gastrointestinal dysfunction: If the baby’s abdomen is cold or eat cold food, it will lead to abnormal peristalsis of the gastrointestinal tract, resulting in gastrointestinal dysfunction, so that the intestinal flora imbalance, so that food can not be adequately absorbed, decomposition, which will result in the baby’s stool smell, may also be accompanied by abdominal pain, diarrhea and other manifestations. 3. Gastrointestinal infection: If the intestinal tract is infected by bacteria and viruses, it will lead to the damage of the mucous membrane of the digestive tract, coupled with a large number of bacterial reproduction and deterioration of intestinal contents, so it will make the baby’s stool stinky, and accompanied by diarrhea, abdominal pain, fever and other manifestations. Five-month-old baby’s stool is very smelly can be caused by physiological reasons or pathological reasons, if there are pathological factors, it is recommended to seek medical attention in a timely manner.