A friend of mine who only just found out she was pregnant two months ago called me earlier this week to chat. During our conversation about all of her prenatal visits and checkups, she mentioned that she was concerned about the amount of white blood cells in her blood test results. Though the blood test was actually for something else entirely, the nurse expressed some surprise at the elevated levels in her body. My friend brought this up to her obstetrician later who seemed to shrug it off, but she was still worried about it. I assured her it couldn’t be a big problem if the doctor didn’t seem concerned, but after we hung up I was curious about the possible cause.

Since white blood cell counts elevate when there is an infection in the body, their elevation in pregnancy could suggest that something is wrong with the amniotic fluid or placenta. Of course, both of those issues would show other symptoms, so it’s no wonder the doctor in my friend’s case didn’t seem very concerned.

When I researched the issue, I learned that it’s actually very common for a woman’s white blood cell count to become elevated during pregnancy because of the changes in the blood vessels. In your usual white blood cell count, many of the cells are not accounted for because they are stuck to the walls of your vessels. During pregnancy, your blood vessels expand and shift, so many of those cells that were not picked up in previous tests are now flowing through the bloodstream and getting counted on the blood test.

Of course, if you’re really concerned you should ask your doctor to check you for any infections or problems. It’s always better to be safe than sorry, especially during your pregnancy. However, if a routine test comes back looking strange with elevated white blood cells and you aren’t experiencing any other symptoms, it’s safe to assume your blood vessels’ expansion is to blame.

I gave my friend the news and she is now relaxed knowing that there is no serious problem that is causing her white blood cell count to be higher. It’s always easy to become overly concerned during your pregnancy, but without that concern we’d end up letting many serious symptoms go by unnoticed. You should trust your doctor’s opinion when he seems okay with a symptom, but follow your instincts.

Source: Richard A Polin et al: Management of Neonates with Suspected or Proven Early-Onset Bacterial Sepsis. The American Academy of Pediatrics Volume 129 Issue 5 pp. 1006-1015 April 2012