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Cytomegalovirus (CMV) Infection: What are the Implications Regarding Pregnancy?

by Dr. Geoffrey Sher on June 12, 2016

Cytomegalovirus (CMV) belongs to the Herpes group and, like Herpes, can remain dormant in the body for long periods of time (even for life). CMV infection is very common, such that by age 40Y >50% of adults will bear evidence of previous infection (i.e. test IgG +…see below). Acute infection most commonly is seen in developing babies, in those who care for or work with children and in people who are HIV positive. CMV infection rarely causes a significant illness or symptoms. People who become infected have the virus lie dormant in their bodies, for life.

There are two types of active (acute) CMV infections: 1) Primary CMV and, 2) Recurrent CMV infection. Primary can elicit more serious problems in pregnancy than the recurrent infection can. During the acute phase, IgM antibodies develop to the virus. After that, a conversion to IgG antibodies takes place.

Transmission of CMV occurs in the active acute phase only. Those who test positive fo CMV-IgG antibodies are not infective. CMV is spread through close, intimate contact with a person excreting the virus.

CMV infections can be diagnosed by looking for IgM antibodies in the blood (signifying an acute attack) or by finding IgG antibodies (pointing to a dormant, past infection). The virus can also be diagnosed by throat, blood urine and semen and tissue cultures.

If a pregnant woman is diagnosed with the CMV infection, amniocentesis can be done to check fetal fluids or blood for signs of infection.

Treatment of acute CMV is by no means definitive but the infusion of intravenous gammaglobulin, to pregnant women with CMV, might prevent fetal infection. Antiviral medications, such as Ganciclovir and Valganciclovir, has also been used with some success to prevent or treat congenital CMV.

Transmission can be avoided by adhering to certain precautionary measures, such as avoiding contact with infected bodily fluids. This includes, safe hygiene practices including good hand washing, with soap and water, wearing gloves when in contact with bodily fluid from potentially infected individuals and the use of condoms when having intercourse with someone suspected of having CMV. There is about a 30-50% risk that a CMV infected pregnant woman will transmit the virus to her developing baby, about 10%-15% of infected babies will develop congenital CMV. If a woman has recurrent CMV during pregnancy there is <1% chance of  newborn CMV infection and fewer than 1 in 10 of these will show symptoms at birth. Another 10-15% may be asymptomatic at birth but subsequently go on to have long term effects such as hearing loss and learning disabilities.

Therefore pregnant women are advised to take precautions to avoid infection with CMV. These include:

  • Be checked for CMV infection if the develop symptoms during pregnancy
  • Practice good personal hygiene and do not share eating/drinking utensils with others

Women with a previous history of CMV can get tested for the condition (cultures and antibody tests).

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