Low urine output of newborns may be caused by physiological reasons, abnormal regulatory function, kidney disease, etc. 1. Physiological reasons: newborns tend to eat less milk, and drink less water, generating insufficient fluid will lead to low urine output. It is also possible that the room temperature is high, resulting in newborns sweating more, the urine concentration will be less urine. 2. Regulatory function abnormalities: due to the immature development of the newborn’s kidney function, the water excretion rate is relatively slow, which will lead to less urine, with the gradual growth and development of the newborn, the amount of urine will return to normal. 3. Kidney disease: for example, congenital kidney malformation will affect the kidney function resulting in low urine. Newborns with low urine output, 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.