Updated December 30, 2014.
Cytomegalovirus, often abbreviated as CMV, is a common virus that rarely causes serious problems for healthy individuals -- with an unfortunate exception being pregnant women and their unborn babies. Although the majority of babies will not experience long-term complications, CMV can sometimes cause serious problems for unborn babies when moms without existing immunity are exposed to CMV in pregnancy.
CMV Statistics:
More than half of pregnant women already have antibodies to CMV (meaning they have been previously exposed). Between 1 and 4% of expecting moms are exposed to CMV for the first time during pregnancy, and of these women, about a third will have babies born with CMV infection. The majority of babies born with CMV will not experience long-term complications, but a small fraction may be severely affected. It is not known why some babies respond differently to CMV infection than others.
Risks of CMV Infection in Newborn Babies:
About 40,000 babies are born each year with CMV infection. Around 90% of these babies do not have active CMV symptoms at birth but may face increased risk of hearing and visual disabilities, so follow-up screening may be recommended. The 10% of infected babies that do have symptoms at birth (jaundice, enlarged spleen, seizures, liver symptoms, and/or a characteristic rash) have a more negative prognosis. Up to 20% of these babies may die due to complications from the infection, and survivors may have up to a 90% risk of developing mental retardation, cerebral palsy, or other serious disabilities.
CMV and Miscarriages:
Some research shows that moms who are exposed to cytomegalovirus for the first time during pregnancy may have a higher risk of miscarriage, but the relationship of CMV to miscarriage is not completely clear at this point. The most serious risk seems to be that the baby could be born with a CMV infection.
Symptoms of CMV Infection in Pregnant Women:
CMV infection frequently causes no symptoms in healthy adults, but some pregnant women may have mild fever, swollen glands, and flu-like symptoms.
Avoiding CMV Infection:
Researchers are attempting to develop a vaccine against CMV but none is currently available. The virus is transmitted via bodily fluids, including saliva and nasal secretions, and CMV is very common in daycare centers. The CDC advises that the best way to prevent CMV infection is regular hand washing and using care in contact with young children. Moms who work in daycare centers during pregnancy and don't know whether they are immune to CMV should use extra caution. Your doctor can run a blood test to tell you if you are already immune to CMV if you are concerned.
What to Do If You Think You Have CMV:
It's a good idea to report any fever during pregnancy or flu-like symptoms in pregnancy to a physician. These symptoms can indicate a number of different infections, many of which can be dangerous in pregnancy, and your doctor will want to evaluate you to determine an appropriate treatment.
If CMV is confirmed as the cause of your symptoms, there is unfortunately no treatment available, but your doctor might want to perform extra monitoring on your baby to catch any complications as early as possible. And although it can be scary to read about the what-ifs that can occur after CMV infection, it's important to remember that the majority of cases do not involve worst case scenarios -- and although there are no guarantees, the odds are better that your baby will not suffer long-term complications.
If you have already given birth to a baby who had a serious case of congenital CMV infection, your future pregnancies will most likely not be affected -- CMV infection usually results from a first-time exposure to CMV during pregnancy only and it is extremely rare for a subsequent pregnancy to be affected.
Sources:
CMV and Pregnancy. CDC. Accessed: Nov 3, 2009. http://www.cdc.gov/cmv/pregnancy.htm
Cytomegalovirus in Pregnancy. March of Dimes. Accessed: Nov 3, 2009. http://www.marchofdimes.com/professionals/14332_1195.asp
Griffiths, P.D. and C. Baboonian. "A prospective study of primary cytomegalovirus infection during pregnancy: final report." BJOG Volume 91 Issue 4, Pages 307 - 315.
Tanaka K, Yamada H, Minami M, Kataoka S, Numazaki K, Minakami H, Tsutsumi H. "Screening for vaginal shedding of cytomegalovirus in healthy pregnant women using real-time PCR: correlation of CMV in the vagina and adverse outcome of pregnancy." J Med Virol. 2006 Jun;78(6):757-9.
Tremblay, Cecile. "Cytomegalovirus infection in pregnancy." UpToDate. Accessed: Nov 2009.
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