Level 1: What are diarrhea and dehydration in babies? Diarrhea in babies refers to an increase in the frequency of defecation in infants and young children, and the volume of stool becomes less and watery, accompanied by uncomfortable symptoms such as nausea, vomiting, and abdominal pain. Dehydration in babies occurs because the body loses a large amount of water and electrolytes during diarrhea, causing a series of symptoms in the body. Level 2: What are the causes of diarrhea and dehydration in babies? 1. Digestive infection: such as gastrointestinal infection caused by bacteria, viruses, etc.; 2. Improper diet: such as adding supplementary food too early or eating too much or too much.