In general, it is normal for the newborn testes to have a lower diameter of about 4 centimeters and a volume of between 15 and 25 milliliters. In newborns, the testes are in a nascent state and basically well formed, and the testes are usually normal with an upper and lower diameter of about 4 centimeters and a volume of between 15 and 25 milliliters. If a newborn’s testicles are abnormally sized, the cause is considered to be testicular syringomyelia and inguinal hernia. Testicular syringomyelia occurs when a small amount of fluid from the abdominal cavity enters the testicular syringomyelia cavity if the syringomyelia is not completely closed after birth. In addition, inguinal hernia in newborns may also lead to abnormal testicular size in newborns. Parents should take their newborns to the hospital for examination if they notice a significant difference in the size of the testicles between the two sides of the newborn, or if the overall size is too large or too small.