A newborn crying while breastfeeding may be caused by physiological reasons or illnesses, such as intestinal cramps, upper respiratory tract infections and so on. 1. Physiological reasons: newborns crying while breastfeeding may be caused by improper breastfeeding posture and discomfort of the baby, or it may be caused by the baby’s impending sleep and irritability. 2. Intestinal spasm: the sudden onset of abdominal pain as the main clinical symptom, in the milk can be caused by increased intestinal peristalsis, intestinal wall smooth muscle contraction, resulting in abdominal pain, crying, or accompanied by vomiting. Between attacks, the child is normal, does not affect the appetite, but when the abdominal pain is severe and frequent attacks, it can affect its spirit and appetite. 3. Upper respiratory tract infection: due to the poor resistance of newborns, immune function is not sound, if you do not pay attention to warmth, it is very easy to lead to upper respiratory tract infection. Inflammatory stimulation can cause increased nasal secretions, blocking the nasal cavity, may affect the baby to eat milk, thus appearing to cry while eating milk. Newborns crying while breastfeeding, to rule out physiological causes, should promptly consult a doctor to clarify the cause of the disease, if necessary, appropriate treatment.