3 months baby does not want to eat milk, may be due to physiological or pathological factors, physiological factors such as physiological anorexia; pathological factors such as acute upper respiratory tract infection, acute gastroenteritis. 1. physiological factors: 3 months of the baby, may be due to growth and development slower than before, the phenomenon of physiological anorexia. Physiological anorexia of the baby will have increased sleep time, decreased milk, but the general situation is good, there is no abnormal performance. 2. Pathological factors: when the baby suffers from diseases such as acute upper respiratory tract infection, acute gastroenteritis, can make the appetite decline, do not want to eat milk. Due to disease, there are other abnormal symptoms, such as acute upper respiratory tract infection and cough, fever and other symptoms; acute gastroenteritis, vomiting, diarrhea and other symptoms. 3 months baby does not want to eat milk, there may be other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.