The cause of sour and smelly poop of newborn babies may be that newborn babies suffer from enteritis or caused by indigestion, as well as physiological factors. 1. enteritis: due to bacterial reproduction in the baby’s body, especially the intestinal E. coli bacteria reproduction caused by enteritis, which leads to the baby diarrhea, sour stool and other symptoms. 2. indigestion: due to the incomplete development of the baby’s gastrointestinal function, when the cold, eating too much or feeding improperly, easy to cause the baby’s gastrointestinal function disorders, which leads to indigestion, the situation of acidic and foul-smelling stools. 3. Physiological factors: breastfed newborns, the stool can be slightly sour odor, but the taste will not be particularly strong. When the baby appeared the symptoms of sour odor, do not panic, you can change the feeding method and appropriate massage abdomen, etc., if there is no relief, to go to the hospital in a timely manner.