Believe it or not, there are some diseases and infections humans can get without even realizing it. By the time you become pregnant, there is a 50% chance that you’ve already contracted something called the cytomegalovirus (CMV) and developed antibodies to it. It sounds like a virus that’s difficult to ignore, but in fact CMV usually comes on with no major symptoms. If you felt any at all, you might have attributed them to a poor night’s sleep or a minor cold. Since CMV is the same type of virus as herpes, it too remains dormant inside the body forever even after the initial flare-up is over. Most women with CMV never notice it unless their immune system is compromised later in life with cancer or HIV.

If you already had CMV before you become pregnant, there is a 1% chance or less that you’ll pass it on to your baby. Even if you do, he or she probably won’t show any symptoms.

However, if you become infected with CMV for the first time while you are pregnant, the level of risk greatly increases. In that case, there is a 50% chance you’ll pass the virus on to your baby in utero, and he or she could suffer serious consequences. He or she might have hearing problems later in life as a result of the infection, or they could even be born with nervous system and neurological problems. The list of potential complications is long, so you should try to avoid the infection when you become pregnant, even if you’re unsure whether or not you have it to begin with.

It’s impossible to tell whether or not you already have CMV without a blood test, but it’s best to err on the side of caution when you become pregnant. CMV is transmitted through bodily fluids, so be extra careful to avoid the saliva, blood, reproductive secretions, urine, feces and even tears of people you don’t already live with. Even sharing silverware can transmit the infection, so think of yourself as the boy in the plastic bubble for the duration of your baby’s gestation. Wash your hands often and limit your physical contact with children under six.

Even if you already have CMV when you become pregnant, try avoiding contact with the bodily fluids of others until you’ve delivered your baby. It will protect you against CMV but will also help you avoid any additional infections.

Source: Y Yinon et al: Cytomegalovirus Infection in Pregnancy. Journal of Obstetrics and Gynecology Canada Volume 32 Issue 4 pp. 348-354 April 2010