3 months old baby usually defecate 1-4 times a day, if 5 days has not pooped, fart very smelly, may be a problem with the digestive system, parents should pay attention to it, and actively respond. Common situations and related recommendations are as follows: 1, functional constipation: three months baby digestive system and nervous system development is not perfect, gastrointestinal function is weak, easy to feed too much milk, milk powder brewed too thick and other reasons leading to indigestion, long-term development caused by constipation, for many days without defecation, burping and exhaust odor, you can use the open plug laxative, follow the doctor’s instructions to apply lactobacillus, bifidobacterium trituberculosis, etc. to assist digestion. Moderately reduce the amount of milk feeding, milk powder brewed lighter, daily attention to the baby abdomen warm; 2, secondary megacolon: If the baby three months without, daily accompanied by vomiting, abdominal distension, foul-smelling exhaust and defecation, decreased appetite and other symptoms, suspected of secondary megacolon, due to the anus, rectal end of organic lesions, such as congenital anal stenosis, post-operative epileptic scar stenosis or extra-rectal tumor compression, so that defecation is not smooth, feces stagnation. Need to go to the pediatric department for rectal finger examination or X-ray examination; after confirmed diagnosis, oral lactulose or topical sorbitol can be used to assist defecation; if the symptoms still cannot be improved, or there is malnutrition, high fever, anemia, etc., early surgery is needed to remove the functional abnormal intestinal segment; 3, intestinal obstruction: if the baby’s fetal stool is normal, accompanied by abdominal distension, vomiting, crying and other manifestations, vomit is fecal residue-like, smelly, and the volume of defecation and exhaustion gradually decreases, it can be suspect that the baby is suffering from intestinal obstruction, the specific cause can be determined by abdominal X-ray or abdominal CT, and conservative medical treatment or surgery can be taken to lift the obstruction.