The main reasons for babies farting and smelling bad are physiological factors, gastrointestinal disorders, indigestion and so on. 1. Physiological factors: if the baby eats too much protein-rich food, then the protein will be decomposed in the intestines to produce methane and sulfur-containing gases, which will lead to the baby’s farts are very smelly. 2. Gastrointestinal dysfunction: Since the digestive system of babies is not perfect, a little external stimulation can cause gastrointestinal dysfunction. For example, eating too much milk or too much food will easily affect the baby’s gastrointestinal function, which will result in smelly farts. 3. indigestion: the baby’s gastrointestinal function is not mature, it is also easy to cause indigestion, resulting in food residue retention in the intestinal tract, the bacterial decomposition, fermentation and odor, bloating, farting odor. As you can see, if the baby farts stinky and accompanied by other uncomfortable symptoms, it is recommended to consult a doctor in a timely manner, according to the cause of the symptomatic treatment.