Five-month-old babies do not urinate all night may be a normal physiological phenomenon, may also be caused by diarrhea, vomiting and other loss of body fluids, the latter need to seek medical attention to clarify the cause of active treatment. 1. five month baby drink less milk, or because of the environment temperature higher sweating, circulating blood volume decreased, can cause urine volume decreased. If you increase fluid intake during the day, the urine output can increase, while the baby does not appear excessive crying, fever and other abnormal manifestations, considered a normal physiological phenomenon. 2. The baby’s first urination behavior after birth belongs to pure reflex urination, after 5~6 months most children can hold their urine and appear overnight without urination. If the amount and frequency of daytime urination is normal, this situation does not require special treatment. 3. If the baby has diarrhea, vomiting and other symptoms, can cause a large loss of body fluids, circulating blood volume decreases, resulting in decreased urine output. At this time, you need to consult a doctor in time, after the cause of the disease is clear and actively target the original disease treatment.