Green stools are very common in small babies before the age of 6 months. They are not indicative of any disease, neither are sign of bad health in anyway especially if your child is feeding and growing well. They can happen intermittently along with normal yellow stools. Usually they stop once we start weaning and giving complementary feeds at 6 months. However children can have green stools during episodes of Acute gastroenteritis ( however they will be associated with loose and watery stools) and will rarely be semiloose or solid in consistency Sometimes even after cold child can have green stools but child will have associated cold symptoms. Basically green colour in stool means bile which is normal fluid in the stomach Also remember a newborn also passes green stool for initial few days which is also normal.