7-year-old baby bad breath, may be physiological factors, indigestion, gingivitis and other factors caused. 1. Physiological factors: generally due to the baby did not develop good hygiene habits, such as not brushing teeth and rinsing mouth after meals. This causes food to remain in the mouth, so the baby will have bad breath. 2. Indigestion: generally due to baby intake of indigestible food, such as fish, shrimp, meat, onions, garlic and other foods. Or eat too many snacks, overeating, etc., the body indigestion is easy to cause gastrointestinal function burden, can also cause bad breath symptoms, accompanied by nausea, abdominal pain. 3. Gingivitis: generally due to poor oral hygiene, tartar and plaque on the teeth, will stimulate the gums and lead to inflammation of the gums. So the patient will appear bad breath, accompanied by bleeding gums, redness, swelling, pain and other symptoms. 7-year-old baby bad breath, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, give targeted treatment or treatment.