The reason why little baby fart stinks is related to physiological factors, indigestion, acute gastroenteritis and other factors, which are analyzed as follows: 1. physiological factors: baby digestive function is not yet well developed, weak digestion, food in the intestinal tract by the bacterial decomposition of the gas produced to produce a large number of farts, can be with odor. 2. Indigestion: the digestive function of the baby is weak, when the food in the body can not be digested and decomposed, the bacteria in the intestinal tract will also increase, the intestinal cavity gas increases, resulting in the phenomenon of smelly farts. 3. Acute gastroenteritis: mostly caused by infected bacteria inflammation of the intestinal mucosa, manifested as abdominal pain, diarrhea and other symptoms, intestinal flora disorders, easy to produce a lot of gas, the baby will let out smelly farts. Caused by the little baby fart odor may also have other reasons, it is recommended to go to the hospital in a timely manner to carry out the relevant examination, clear cause of the disease after active symptomatic treatment.