Cytomegalovirus infection-what are the risks in pregnancy?

Cytomegalovirus (CMV) is a virus belonging to the Herpesviridae family. As many as 8 of its species are known to be capable of causing infection in humans. It has one of the largest genomes among microorganisms and can code for hundreds of proteins. It enters the host by attaching its glycoproteins to receptors present on human cells. The pathogen is widespread around the world – most infections are reported in developing countries, among groups with low socioeconomic status. Cytomegalovirus is very dangerous for the fetus.

Cytomegalovirus – what is the disease?

Cytomegalovirus is a disease caused by cytomegalovirus. It covers the entire body. It can appear at any age. It occurs in both children and adults. It is estimated that up to 70% of toddlers become infected from their peers during their preschool years. Parents are the source of the pathogen for infants. In contrast, about 1% of all infections are congenital, which can occur at any stage of pregnancy.

In most people whose immune systems are functioning properly, cytomegalovirus does not cause any symptoms. In some cases, cytomegalovirus infection manifests as cytomegalovirus mononucleosis. The following symptoms are then observed:

• enlargement of lymph nodes,
• liver enlargement,
• Muscle and joint pain,
• fever,
• general weakness.

Symptoms resolve spontaneously after a few days and usually leave no sequelae. Cytomegalovirus infection can also take the form of viral hepatitis. In such cases, adults may develop jaundice. In contrast, a significant weakening of immunity (such as that caused by HIV infection) results in a more severe course of the disease. Patients develop interstitial pneumonia, retinitis, encephalitis. The organs of the digestive system are also involved.

Cytomegalovirus in the human body penetrates the endothelium. It also occupies cells of the immune system: leukocytes and lymphocytes. The infected person’s body produces IgM and IgG class antibodies.

How does cytomegalovirus infection occur?

Sources of cytomegalovirus infection include all body fluids, especially saliva, genital secretions, blood, urine, semen and breast milk. The carrier of the pathogen passes it to another person upon direct contact. Hence the huge risk of transmission to the fetus (through the placenta) and even during delivery. It is difficult to protect against cytomegalovirus, so during pregnancy it is better to avoid direct contact with people, mainly children, who are at risk.

The most common source of cytomegalovirus infection for pregnant women is children under 2. year of age. This is because many of them are asymptomatic carriers. On average, they excrete the pathogen in saliva or urine for 24 months. The risk increases with very frequent and prolonged contact. That’s why mothers of preschool-aged children, as well as nursery and daycare workers, are particularly vulnerable.

Importantly, cytomegalovirus is common in the community. It is estimated that up to 80% of the adult population is an asymptomatic carrier. In their case, the pathogen remains in the body’s cells in an inactive form. Most go through the infection very mildly or do not develop any disease symptoms.

Statistics indicate that up to 90% of women of reproductive age have come into contact with cytomegalovirus. Most of them are unaware of the carrier due to the lack of any complaints. However, it is worth remembering that a dormant virus can activate – this usually occurs when immunity is lowered. Re-activation in the mother’s body is also dangerous for the developing fetus. However, in such a situation, there is a low risk of transmission of the pathogen to the child (compared to an infection that first occurs during pregnancy).

What are the symptoms of cytomegalovirus in pregnancy?

Cytomegalovirus in pregnancy is mostly asymptomatic. The complaints that occur do not clearly indicate a cytomegalovirus infection and can be misinterpreted as a cold, flu or other upper respiratory tract infection. The mother-to-be often does not know that the virus has entered her body until she has laboratory tests.

What are the risks of cytomegalovirus in pregnancy?

Cytomegalovirus in pregnancy is dangerous primarily to the baby developing in the uterus. Infection can occur at any stage of pregnancy and during natural childbirth. The side effects of the infection manifest themselves at different times. Some of these are observed as early as the neonatal period. Some only in the preschool or school years.

Cytomegalovirus in pregnancy can lead to, among other things:

• birth defects in the child,
• restrictions on intrauterine fetal growth,
• progressive hearing loss,
• psychomotor development delays,
• mental development delays,
• eye damage,
• smallheadedness,
• weakened muscle tone,
• hydrocephalus,
• nystagmus,
• anemia,
• epilepsy,
• gastrointestinal diseases,
• cerebral palsy.

It also happens that cytomegalovirus in pregnancy does not lead to disorders in the child. A particularly dangerous situation is when the infection occurs in the first trimester. This is the period when most internal organs and systems – especially the nervous system – are shaped and developing.

How to recognize cytomegalovirus in pregnancy?

Cytomegalovirus in pregnancy can be diagnosed by blood laboratory tests. The diagnosis is made when specific IgM and IgG class antibodies are present in the blood. Their presence, however, does not indicate that contact with the pathogen has already occurred during pregnancy.

At the same time, it is important to remember that the presence of antibodies in the mother does not mean that the child is infected. The first signs of virus transmission can be seen in an ultrasound (USG) examination. The doctor sees abnormalities in the anatomical development of the fetus (such as microcephaly). It is also possible to perform an amniocentesis to detect cytomegalovirus in the amniotic fluid.

When to test for cytomegalovirus in pregnancy?

It is recommended to test for cytomegalovirus in pregnancy during the first trimester. It is worth remembering that this is not a mandatory test and provided for in the testing calendar. Therefore, the desire to carry it out should be discussed with the doctor in addition. Performing a test for cytomegalovirus in pregnancy is advisable for all moms-to-be. Some women choose to do so while still in the planning stages of pregnancy.

It is also advisable to test for cytomegalovirus in pregnancy when a woman observes symptoms of infection in herself. It is necessary to inform the attending physician, who will decide on further management.

Is cytomegalovirus in pregnancy an indication for cesarean section?

During natural childbirth, there is a risk of the baby being infected with cytomegalovirus. Therefore, for women with an infection confirmed by laboratory tests, doctors usually decide to perform a cesarean section. In this way, the risk of pathogen transmission is reduced.

Treatment of cytomegalovirus in pregnancy

Treatment of cytomegalovirus in pregnancy is implemented when symptoms of the disease are present. Therapy is based on alleviating the discomfort. Antiviral drugs (those that inhibit the multiplication of the virus) cannot be given to a pregnant woman, as they can be dangerous to the developing baby. An infection that is asymptomatic usually carries no complications for the mother. Cytomegalovirus in pregnancy is dangerous primarily to the fetus.

To date, there is no known treatment for congenital cytomegalovirus in a child. The toddler should remain under close medical care. Taking action is aimed at alleviating symptoms. Regular ophthalmological, audiological and neurological examinations are necessary.

Cytomegalovirus and cord blood banking

An important question is what cord blood banking looks like when confirming cytomegalovirus in pregnancy. In this case, the collected material does not have to be discarded. The decision should be made after consultation with an infectious disease specialist.

What about women who have not been tested for cytomegalovirus during pregnancy? Each collected cord blood is tested in the stem cell bank’s laboratory. If antibodies to cytomegalovirus are detected, the decision to reject the material is also not always made. On the other hand, it is necessary to perform additional tests to determine whether the child has congenital cytomegalovirus.

How to prevent cytomegalovirus infection during pregnancy?

Preventing cytomegalovirus in pregnancy is difficult due to the prevalence of cytomegalovirus in the community. The basis is strict adherence to hygiene. The most important rules are:

• Frequent hand washing with warm soapy water (especially after returning home, after contact with children, after diaper changes, contact with children’s toys),
• Avoiding using the same cutlery with the child,
• Avoiding drinking from the baby’s cups and bottles,
• Avoiding very close contact with children (especially kissing),
• Frequent disinfection of surfaces and objects (especially those that have been in contact with the child’s saliva).

Unfortunately, there is no vaccine that can protect against cytomegalovirus infection. Research is still underway to create it. There is also no screening among the public to identify individuals who carry the virus. What is certain, however, is that the majority of the population is an asymptomatic carrier. It is also worth remembering that the presence of antibodies in the body against the cytomegalovirus does not protect against reinfection.

Very important is the fact that there is no contraindication to breastfeeding if cytomegalovirus is detected in the milk. The child may become infected this way. However, in most cases the infection is asymptomatic.