Three-month-old babies with green poop should be considered in terms of breastfeeding, fast bowel movements and high levels of iron in the formula. 1. Breastfeeding, for breastfed babies, this is a very normal phenomenon. Because the digestive juices contain bilirubin and bilirubin, after mixing with food, a chemical reaction is formed, which may lead to the baby’s green stool. 2. Intestinal peristalsis is too fast, resulting in bilirubin can not be reduced to bilirubin with the stool out of the body, can also lead to this phenomenon. This is often accompanied by symptoms of diarrhea. 3. Milk powder contains high iron, the baby can not fully absorb the iron, resulting in the remaining iron with the stool directly out of the body, will also lead to the baby’s stool green. Therefore, there is no need to worry about this situation. Of course, if your baby has diarrhea at the same time, you need to see a doctor as soon as possible.