Newborns in general have a much higher white blood cell count than adults. Upon birth, a newborn's white blood cell count will be closely monitored. An elevated level or increasing level can indicate an infection, trauma or another disease. White blood cells help the body fight off infections and harmful bacteria in the body.
After birth, a newborn is very susceptible to infections and illness. An elevated white blood cell count allows babies to fight off these predators, but these levels will go down within two weeks or so once they become used to their surroundings.
Normal white blood cell counts in adults ranges from 5000 to 8000, but that number is 12 to 15 times higher in newborns. Newborn white blood cell counts elevate quickly because of the trauma and stress of birth. Their body responds to the new environment by quickly elevating the white blood cell count in the body to fight off new bacteria and keep infections from developing.
At the ensuing checkups for a newborn baby, white blood cell counts will be checked again to make sure they are going down. If the white blood cell count has not gone down, or has gone higher, it could indicate an infection or other disorder. More tests will need to be done on the newborn to better diagnose the problem.
An elevated white blood cell count is called leukocytosis. If a white blood cell count is detected, it must be closely monitored to be sure the levels come down. Otherwise, there could be a much more serious problem at hand. Leukemia is one issue that must be ruled out immediately if there is no other infection or problem present based on other tests.
Once white blood cells become elevated, they should return to normal levels within two weeks. If the levels in a newborn do not subside within this time, the pediatrician may schedule additional testing to rule out other possibilities.