Nine-month-old babies with loose stools may be related to the digestive system is not fully mature, cold, infectious enteritis and so on. 1. The digestive system is not fully mature: the baby’s digestive tract is not very well developed, in the addition of complementary foods if more types, causing digestive disorders, will be the case of dilute stools. 2. Cold: it may be due to climate change, causing the baby’s abdomen to be cold, resulting in increased intestinal peristalsis, inducing intestinal dysfunction and diarrhea. 3. Infectious enteritis: may be bacteria or viruses and other pathogenic bacteria caused by intestinal infections, pathogenic bacteria damage intestinal microvilli, causing intestinal wall edema, leading to the baby’s diarrhea. 9 months baby dilute stool can also be seen in other reasons, it is recommended that timely medical attention, follow the doctor’s instructions for relevant examinations, in the doctor’s help to clarify the cause, and targeted treatment or treatment.