What causes bad breath in babies?

Bad breath in babies may have various causes. 1. Poor oral hygiene is a common cause; food debris and soft deposits accumulating on the tooth surfaces can produce an acidic, foul odor due to bacterial action. 2. Babies with weak gastrointestinal function may experience indigestion or gastroesophageal reflux, which can also lead to bad breath. 3. A baby's dietary habits may affect breath odor—consuming excessive oily or hard-to-digest foods, or overeating leading to food stagnation, may all contribute to bad breath. Oral diseases such as dental caries and gingivitis are also common causes of halitosis. 4. Respiratory tract infections such as bronchitis or pneumonia may impair digestive system function and consequently result in bad breath. Therefore, parents should pay attention to their baby's oral hygiene and eating habits, and watch for symptoms of oral or respiratory diseases. If necessary, timely medical evaluation is recommended.