Five-month-old baby low fever may be the physiological response of the thermoregulatory center function is not complete, may also be due to colds, urinary tract infections, food accumulation and other causes, it is recommended that the patient seek medical attention to identify the cause of the disease. 1. physiological: five months baby body function development is not complete, sweat gland development immaturity, thermoregulation center function is not stable, may in part of the time will make the baby body heat production is greater than heat dissipation, so low fever. 2. Disease factors (1) colds: five months baby immunity is usually lower, in the accidental wind and cold may cause a cold, so the symptoms of fever. (2) urinary tract infection: five-month-old babies may have a urinary tract infection due to friction from diapers, and the accumulation of urine and faeces that are not handled in a timely manner, leading to bacterial infections that can lead to feverish symptoms. (3) Accumulation of food: five months when the digestive system is not yet functioning well, overfeeding is easy to cause accumulation of food, thus causing fever. The causes of low fever in five-month-old babies are usually more, it is recommended that the patient consult a doctor for diagnosis in a timely manner, to clarify the cause of the disease, and then follow the doctor’s instructions for treatment.