Five-month-old baby milk suddenly reduced may be in the anorexia period, is a normal situation, may also be indigestion, gastroenteritis and other diseases. 1. Normal: anorexia is a normal phenomenon in the process of growth and development of infants, usually occurring at 3 to 6 months of age, the main manifestation of the refusal to contain the nipple, pacifier, etc., which will result in a sudden decrease in the baby’s tolerance. 2. indigestion: five months baby milk suddenly reduced may also be indigestion caused by the etiology of infection, environmental factors, psychological factors, etc., the child will appear epigastric pain, postprandial feeling of fullness, early satiety and other symptoms. 3. Gastroenteritis: gastroenteritis is a variety of causes of inflammation of the gastrointestinal mucosa, etiology and infection, stress, drugs, etc., the child will appear epigastric pain, diarrhea, bloating, early satiety and other symptoms, which led to a sudden decrease in milk. There are more reasons for the sudden decrease in milk production of five-month-old babies, and after excluding anorexia, it is recommended to consult a doctor for examination and a clear diagnosis.