CMV infection

Cytomegalovirus and its significance during pregnancy

Cytomegalovirus (CMV) belongs to the herpesvirus family – once infected, it remains in the body for life. In healthy adults, an infection usually goes unnoticed or presents with mild, flu-like symptoms. However, for unborn children, premature infants, or people with weakened immune systems, a CMV infection can have serious consequences.

In Western countries, the infection rate is between 40 and 70%. This means that approximately one in two people has been exposed to the virus at some point in their lives and develops antibodies.

Transmission Routes and Risk Groups

The virus spreads through droplet or smear infection, meaning it is transmitted via bodily fluids such as saliva, urine, blood, or tears, for example, through coughing or sneezing, but also through contact with contaminated objects like pacifiers, toys, or diapers.

An acute infection often resembles a flu-like illness with fever, fatigue, and body aches – but often goes unnoticed. An infection becomes particularly dangerous when it occurs for the first time during pregnancy. Depending on the timing, the risk of transmission to the child and the severity of potential consequences vary.

Children can shed the virus for weeks to months after an infection. For this reason, pregnant women who have close contact with young children but have previously tested negative for CMV should be especially careful. (A negative CMV status is also frequently the reason for a work restriction if close contact with children is a professional requirement, such as for kindergarten teachers or pediatricians.)

Transmission risk during pregnancy

The likelihood of transmission to the unborn child (congenital CMV infection) depends significantly on the timing of the mother's initial infection:

Stage of pregnancy

Transmission rate

Risk of harm to the child

1. trimester (weeks 1–12 of pregnancy)

approx. 30%

High – 20–30% of children are symptomatic

2 Trimester (Weeks 13–26)

Approx. 38%

Moderate – 6–10% with symptoms

3. trimester (from week 27 of pregnancy)

Up to 72%

Low incidence – usually mild course

Although the risk of transmission increases later in pregnancy, the likelihood of serious health consequences in the newborn decreases.

Possible Symptoms and Long-Term Consequences of Congenital CMV Infection

Approximately 10–15% of infected children show symptoms at birth, including:

• Microcephaly (reduced head circumference)

• Calcifications in the brain

• Enlarged liver and spleen

• Blood count abnormalities, jaundice

• Growth retardation

• Eye abnormalities (e.g., retinitis)

Long-term consequences can also affect children who initially appear normal at birth.

These include:

• Hearing loss (affects 5–15% of all congenitally infected children)

• Speech and developmental delays

• Visual impairments

• Learning disabilities, cognitive impairments

• Epileptic seizures

Therapy: Antiviral treatment – ​​what do the studies say?

Symptomatically infected newborns can be treated with the antiviral drug valganciclovir. Studies show that a six-month course of therapy:

• can slow or mitigate hearing loss,

• and improve neurological development compared to untreated children.

Efficacy is particularly well-documented when treatment begins within the first few weeks of life. Antiviral therapy is not currently recommended for asymptomatic children, as the benefits and risks are not yet fully understood. Treatment requires close medical monitoring due to potential side effects (e.g., changes in blood cell counts).

How can pregnant women protect themselves from CMV?

There is currently no vaccine against CMV. Therefore, consistent hygiene measures are the most important protection.

• Wash your hands regularly, especially after changing diapers, wiping noses, or feeding young children

• Do not share cutlery, pacifiers, or drinks with young children

• Avoid kissing on the mouth

• Have your CMV status checked: An antibody test at the beginning of pregnancy can indicate a previous infection or, in the case of a later infection, allow conclusions to be drawn about the time of infection. Unfortunately, CMV antibody testing is not covered by statutory health insurance. Gynecologists are supposed to inform all pregnant women about the possible consequences of a CMV infection; however, at the beginning of pregnancy, so many other questions are often relevant at once that details about CMV are not discussed and are therefore not even known to the patients.

Conclusion

CMV is one of the most common infectious diseases during pregnancy, but it often goes unnoticed. However, an infection can have significant health consequences for the unborn child, most notably hearing loss or developmental delays. In fact, congenital CMV infection is the most common non-genetic cause of hearing loss in children. Therefore, targeted preventative measures in everyday life are crucial, especially when in close contact with young children. A simple hygiene routine can make a big difference – for the health of both mother and child.