Level 1: What are the causes of diarrhea in babies? Diarrhea in babies refers to an increase in the number of defecation times in infants and young children, and the stool becomes thin or watery, accompanied by varying degrees of diarrhea, abdominal pain and other symptoms. There are many causes of diarrhea in babies, including infection, improper diet, allergies, imperfect digestive development, etc. Infection causes babies to have diarrhea