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Skip Navigation LinksCytomegalovirus (CMV)
Page modified at: 14/03/2010

Cytomegalovirus (CMV)

This information is about the risks that exposure to cytomegalovirus can have during pregnancy. With each pregnancy all women have a 3% to 5% chance of having a baby with a birth defect. This information should not take the place of medical care and advice from your health care provider


What is cytomegalovirus

CMV is a member of the herpes family of viruses and is primarily a sexually transmitted disease but it can also be transmitted from mother-to-child congenitally through blood transfusions, by close personal contact and via organ transplantation

CMV spreads from one person to another through contact with saliva, semen, cervical and vaginal secretions ,blood , urine , tears , faeces, or breast milk.

The rate of CMV infection in women varies from 50-80%25. A healthy immune system keeps this virus in check. There are two different types of infection primary CMV infections and recurrent CMV infections.


Who is at increased risk for CMV?

Women who work in day-care centres or women who are exposed to toddlers and young children have an increased risk of CMV infection. Women who work in the health-care profession may also be at an increased risk although the transmission to a health professional from an infected patient has never been documented.


How can I find out if I am infected with CMV

A blood test can determine if you have a non-active latent CMV infection. Ideally testing should be done prior to conception. If an infection is identified during pregnancy several tests may need to be performed to determine whether the infection is new primary or old recurrent. You should discuss whether you should be tested with your health care provider. Because testing for CMV infection can be difficult to interpret your test may need to be performed at a special laboratory.


What precautions can I take to avoid CMV infection

Women of childbearing age should practice good hygiene especially if they are routinely exposed to young children. Good hand washing after changing diapers and after any contact with any of the bodily fluids mentioned above is encouraged. Mouth-to-mouth kissing with children attending day-care is discouraged. Pregnant women should refrain from sharing food eating utensils and drinking utensils. All women with non-monogamous relationships are strongly encouraged to use latex condoms during intercourse.


I am pregnant and have just found out that I have recently been infected primary infection with the CMV virus. Is my fetus at risk?

Primary maternal infection occurs in 0.7-4.0%25 of pregnancies. The reported transmission rates to the fetus are between 24 and 75%25 with an average transmission rate of about 40%25. Fetuses that become infected during pregnancy are said to have  “congenital CMV infection”. Of the approximately 40%25 of fetuses that become infected 10%25 of neonates show symptoms of congenital CMV infections after primary maternal infection at birth. The brain eyes liver spleen blood and skin are at risk for problems. Long-term effects may include sensorineural hearing loss mental retardation developmental delay and visual impairment. Of the remaining 90%25 with asymptomatic no evidence of disease at birth congenital infection 5-15%25 are at risk to develop some of the long-term effects. Discuss with your health care provider whether you should see a specialist for further information.


I had a CMV infection a year ago and I was recently diagnosed with a recurrent infection. I am pregnant. Is my fetus at risk?

Recurrent maternal CMV infection occurs 1-14%25 in women more commonly than primary CMV infection but only 0.2-2%25 of recurrent infections produce congenital infection. The incidence of symptomatic neonatal disease after recurrent maternal CMV infection is quite low less than 1%25 but long-term effects may still occur in 5-10%25 of congenital CMV infections with sensorineural hearing loss being the most common effect. Discuss with your health care provider whether you should see a specialist for further information.


Does it matter when in my pregnancy I am diagnosed with a primary or recurrent CMV infections?

Gestational age has no influence on the risk of transmission to the fetus. However the severity of the disease tends to be worse when the infection takes place before 20 weeks of gestation. This is true for primary maternal infections more so than recurrent maternal infections. Recurrent maternal CMV infections typically cause no effects that are clinically apparent in the neonatal period regardless of timing of the infection, however there are a few reports of recurrent maternal CMV infections in which the neonate showed clinical signs of infection.

How can I find out if my fetus has been infected with CMV

Once you have been shown to be infected there are several ways to check if your fetus has been infected. Amniocentesis can be performed to check the fluid around the fetus or fetal blood can be examined to determine the presence of infection. Testing the fluid around the fetus has been determined to be more accurate than fetal blood testing. However if the fetus is infected these tests cannot tell you the severity of the infection in the fetus. In some cases infected fetuses may have visible signs of problems on ultrasound such as a decreased amount of amniotic fluid oligohydramnios smallness in size for the fetus’s age intrauterine growth retardation and enlarged tissues in the brain cerebral ventriculomegaly to name a few. After birth a saliva urine or blood test can be performed on the baby. You should discuss these tests with your health care provider.

Is there treatment for CMV during pregnancy?

Maternal CMV infections may be treated with one of two drug ganciclovir or foscarnet. Unfortunately there is no accepted prenatal or postnatal therapy for congenital CMV infections. The use of ganciclovir during pregnancy to prevent or reduce the effects of congenital CMV infection has been considered. Current recommendations limit the use of ganciclovir in pregnancy to severe life-threatening or sight-threatening maternal CMV infections. Your health care provider can discuss specific treatment options with you.



Adler S et al. 1996. Prevention of child-to-mother transmission of cytomegalovirus by changing behaviors; a randomized controlled trial. Pediatr Infect Dis J 240-246.
Ahlfors K et al. 1981. Secondary maternal cytomegalovirus infection causing symptomatic congenital infection. N Engl J Med. 305, 284.
Azam A et al. 2001. Prenatal diagnosis of congenital cytomegalovirus infection. Obstet Gynecol 97; 443-448.
Boppana S et al. 1999. Symptomatic congenital cytomegalovirus infection in infants born to mothers with preexisting immunity to cytomegalovirus. Pediatrics. 104,55-60
Demmler G. 1992. Acquired cytomegalovirus infections. In Feigin RD, Cherry JD. Textbook of Pediatric Infectious Diseases. PhiladelphiaW.B. Saunders Co.
Ho M. 1991. Cytomegalovirus: Biology and Infection. New YorkPlenum Medical Book Co
Nelson C and Demmler G. 1997. Cytomegalovirus infection in the pregnant mother fetus and newborn infant. Clinic in Perinatology
Piper J and Wen T. 1999. Perinatal cytomegalovirus and toxoplasmosis: challenges of antepartum therapy. Clinical Obstetrics and Gynecology

For further information see the CMV UK Support Website.