Green stools with a foul odor may be due to indigestion, incomplete digestion of food due to increased bowel movements, or infection.
Normally, babies have dark green stools after birth, but they do not have a foul odor. This is because babies are often breastfed after birth and their stools are acidic, while their gastrointestinal function is still immature, so they appear green.
The immature intestinal function of infants, if the replacement diet is not appropriate, improper addition of complementary foods, will lead to indigestion; infants cold, especially the abdomen, will lead to intestinal peristalsis accelerated, food digestion is incomplete that is excreted; or children with infections, such as rotavirus infections will lead to intestinal dysfunction, resulting in acute enterocolitis.
All three of these conditions can lead to fecal fermentation in the intestines or in the air, accompanied by a foul odor.
In this case, you should take the advice of your doctor, drink plenty of water, breastfeeding time should be regular and add complementary food in time, and take oral probiotics to regulate the condition if necessary.
If the stools are green and have a foul odor, it is advisable to consult a doctor.