Pregnant or Planning to Be? You Need to Know About This Under-the-Radar Virus

If the last year and a half has taught us anything, it's that we have probably never been quite conscientious enough about infectious diseases. This is why now, as a doctor and mother of two young children, I cringe remembering birthday parties of yore when snotty 3-year-olds blew out candles (sharing a lot more than just their cake).

While many people now have an acute awareness of germs, in my field of ob-gyn, a heightened awareness of infections during pregnancy is nothing new.

For example it's relatively common knowledge now that people can experience worse outcomes during pregnancy for viruses like the flu, but most patients are not as familiar with another incredibly common virus: cytomegalovirus, or CMV. This is likely because if you're not pregnant, CMV just feels like a bad cold or nothing at all, and is pretty widespread. In fact it's actually far more prevalent than the more widely known Zika virus, which is also part of the CMV family. Some studies estimate that as many as 86% of women of childbearing age have already had CMV at some point in their lives.

Contracting the virus during pregnancy, however, can be dangerous to the developing fetus, and have lasting effects including hearing loss and developmental delays. The good news here is that although CMV is the most common congenital viral infection in the US, it's still pretty rare for a fetus to contract it and become symptomatic, and only 2-3% of pregnant people are known to get it for the first time during pregnancy.

"CMV is such a difficult virus to navigate in the obstetric world," says Natalie Aziz, MD, associate professor in obstetrics and gynecology at Stanford University and a specialist in reproductive infectious disease. "The problem is that it's so ubiquitous and transmittable, but there is no standardized treatment to prevent its transmission in pregnancy. We don't have a good way of preventing or treating it."

The reason CMV is so prevalent is because you can contract the virus through literally every possible avenue: saliva, urine, blood, semen, breast milk, and even tears, but providers do not routinely test for it. In order for a screening test to be clinically valuable, Dr. Aziz explains, the disease has to be both prevalent and treatable. The problem with CMV is that while the former is true, the latter is not.

In reality, we really only test a small percent of pregnant people for CMV. This includes people who have known contact with the virus (say, through a daycare outbreak), people with unexplained flu-like symptoms, and people with specific worrisome fetal ultrasound findings, like extra fluid around the heart and bowel, and abnormalities with the brain.

On the other hand, knowledge is power and just being aware of a potentially dangerous virus during pregnancy might actually change behavior such that you take extra hygienic precautions. Thoroughly washing your hands for at least 15 to 20 seconds and avoiding any activity where saliva can be exchanged are small but helpful prevention methods, according to the National CMV Foundation.

Chances are, if you're pregnant or trying to conceive right now, you're likely already taking every possible step to stay healthy. Vita Berger, MD, assistant professor in maternal-fetal medicine at the University of California, San Francisco, says that's the right idea, even though "the risk of acquiring CMV and the risk of transmission to the fetus is relatively low." So, if you're pregnant or planning to be? It may never have to be more than a quick question to your OB.