Congenital cytomegalovirus (CMV) and birth defects

Cytomegalovirus is a very common member of the herpes virus family. By the age of 40, half of the adult population is infected with cytomegalovirus. Usually, cytomegalovirus infection is short-lived, causes no noticeable symptoms, and then remains in the body for life. But what if a pregnant woman becomes infected with cytomegalovirus for the first time during pregnancy, or if she has a recurrence of the infection from a previous exposure? Are there any risks to the fetus? And if so, how can your healthcare provider help minimize these risks?

In this article, we will discuss birth defects associated with CMV and how to protect yourself and your growing baby. If you want to know more about cytomegalovirus in pregnancy in general, see our article Cytomegalovirus Infection.

Congenital malformations of cytomegalovirus in the womb

Not all children born to mothers infected with cytomegalovirus develop CMV, and not all who become infected with cytomegalovirus experience long-term effects. However, it is important to be aware of the risks, as some of them may affect how your child lives their life.

What is the risk of passing cytomegalovirus to my baby during pregnancy?

This makes cytomegalovirus the most common congenital viral infection. While this seems like a large percentage of births, only 1 in 5 babies born with CMV will experience adverse symptoms or long-term problems.

The virus can travel in the mother's blood and cross the placenta, infecting the developing baby.

If you contracted the virus before you became pregnant: The chance of passing it on to your baby is very low. The risk is increased if you have been re-infected with a different strain of the virus or if you have reactivated the virus during pregnancy.

If you contract the virus (primary infection) during pregnancy: Cytomegalovirus is more likely to be passed on to your baby if you contract a primary infection during pregnancy than if you were already infected. If you have a primary cytomegalovirus infection during pregnancy, there is about a 40% chance of passing the virus to your baby.

The risk of mother-to-child transmission is highest if she acquires a primary cytomegalovirus infection during the third trimester (40-70%) and lowest if the primary infection begins during the first or second trimester quarter (30-40%).

Can CMV harm my developing baby?

Cytomegalovirus can be passed to your baby at any time during pregnancy, and any congenital symptoms of cytomegalovirus present after birth develop in the womb. So in a way, yes, cytomegalovirus can harm your developing baby.

However, the risk of fetal death from cytomegalovirus infection is extremely low. Doctors have seen fetal seizures after infection with CMV, but most of these babies are able to survive and thrive long after birth.

There are many abnormal ultrasound findings that may indicate CMV infection, including but not limited to:

Organomegaly (abnormal organ enlargement) – spleen, liver, and others
Abnormal dilation of lateral brain ventricles, the ureter, and/or the renal pelvis
Intracranial calcifications
Microcephaly
Placental thickening
Fetal hydrops
Ascites
Hepatic, intestinal, or periventricular echodensities

One or more of these may indicate CMV; however, many of these abnormalities are associated with a variety of other diseases or syndromes.

If there is concern, are there tests to check my baby's cytomegalovirus status in utero?

Yes, there is a test that can determine the CMV status of your growing baby while still in the womb. This procedure is called an amniocentesis, which involves inserting an ultrasound-guided needle into the amniotic sac to take a sample of the amniotic fluid for analysis. Amniocentesis is used to diagnose a number of abnormalities or genetic diseases.

This test is usually done shortly before delivery (late 3rd trimester) or between 14 and 20 weeks. Although an amniocentesis can give parents and doctors a better idea of what problems or defects a child may have, the procedure comes with some risks:

Miscarriage (1/200 – 1/400 pregnancies using amniocentesis)
Infection
Amniotic fluid leakage or full break of the sac
Accidental poke of the fetus with needle
Potential to mix the mother’s blood with fetus’s

If any abnormalities are found on the ultrasound, talk to your doctor about your options and the risk to you and your baby with an amniocentesis. Many times the benefits of knowing the results outweigh the risks. This is a personal decision that your doctor cannot make for you, although he may suggest a specific route.

Perhaps the biggest advantage of determining a child's CMV status is the ability to quickly treat after birth. If symptoms of CMV are present, the baby may receive antiviral treatment sooner than if tests were only done after birth.

Is there any treatment if my child is diagnosed with CMV in the womb?

While there are few, there are several possibilities that you and your doctor(s) can explore after you know from an amniocentesis that your developing baby has CMV.

It is important to remember that not all options are available to everyone and may depend on your doctor or hospital, the availability of the treatment offered, your medical history, stage of investigation at a particular clinic, and/or your ability to travel.

Sometimes the best treatment plan is to wait until birth to start antiviral therapy for the baby.

What birth defects are associated with CMV?

The main ways in which CMV can affect a child immediately or explicitly are:

Hearing loss
Mental disability
Seizures
Vision loss
Decreased muscle strength (including cerebral palsy)
Decreased coordination
Microcephaly

However, it is important to remember that most babies born with cytomegalovirus do not suffer long-term effects or conditions.

What can I expect after giving birth?

If you and your doctors know that you had a reactivation of the virus or a primary infection with cytomegalovirus during pregnancy, they will take a saliva, urine, or blood sample from your baby during the first 2 to 3 weeks of life to determine if your baby has CMV. These tests check for live virus or viral DNA rather than antibodies because the first two are more accurate. They will also look for signs of cytomegalovirus in your newborn.

Approximately 10% of infants who test positive for CMV will have symptoms associated with CMV presenting at birth:

microcephaly
pre-term birth
low birth-weight
seizures
problems with or an enlarged liver or spleen
hearing loss

Of the 10% who have symptoms at birth, 40-60% will have long-term difficulties such as:

hearing loss
mental disability
vision loss
seizures
coordination loss
decreased muscle tone or ability (including cerebral palsy)
calcifications in the brain
feeding or sleeping issues
death (very rare)

Hearing loss appears to be the only difficulty that may develop later in infants with CMV who are asymptomatic at birth. This represents about 10-20% of infants with cytomegalovirus who are asymptomatic at birth.

So in the review:

10% of babies with CMV who are symptomatic at birth will have some form of long-term difficulty.
10-20% of children with CMV who are asymptomatic at birth will have some degree of long-term hearing loss.

Treatment of CMV

Are there treatments for children born with symptoms of CMV?

Aside from treating the symptoms, the only treatment currently available is antiviral drugs. Ganciclovir and valganciclovir are two antiviral drug options, but both have potentially serious side effects. However, if approved by your pediatrician, this can be a helpful and necessary step for your family.

Both of these antivirals can prevent initial symptoms from turning into more serious long-term effects. This does not mean that all symptoms will go away, but it may mean a reduction in severity, especially in cases of hearing loss and developmental problems.

What does a diagnosis of CMV mean for my baby, even if they don't have symptoms at birth?

Babies who are diagnosed with CMV after birth but have no symptoms may not have long-term problems. However, because some are known to develop over time, these children receive regular scheduled hearing and vision checks throughout childhood and adolescence.

Because developmental (mental) delays can also occur months or years after asymptomatic onset at birth, your baby should be monitored for any signs of developmental disabilities as they grow.

Are there resources to help me as a parent of a child/infant living with a permanent disability due to cytomegalovirus?

Yes, I have! There are many CMV organizations that help parents and their sick children manage symptoms and change lives.

Prevention of cytomegalovirus before and during pregnancy

It is hard to believe that there are so many problems with CMV in the world today that it is actually a preventable disease. Before and during pregnancy, you can take basic hygiene measures to avoid infection. Before pregnancy, you can find out your cytomegalovirus status.

Before getting pregnant

Since you and your partner are planning to become pregnant, it is helpful to be aware of your own cytomegalovirus status. You can do this by asking your doctor to test for cytomegalovirus antibodies for IgG and IgM (two types of antibodies).

If you test positive for a primary infection (IgG and IgM+), it is recommended that you wait until your IgM levels are low enough to indicate a non-primary infection before trying to conceive.

If you are not infected (IgG and IgM-) or if you have evidence of a non-primary/prior infection (IgG+ and IgM-), there is usually no reason to wait to try to design. If there has been no previous infection, the biggest concern during pregnancy is a new cytomegalovirus infection (for prevention tips, see the After section).

After pregnancy

There is no guarantee that you will not become infected with cytomegalovirus or experience reactivation. However, here are some things you can do or avoid to reduce your risk of primary cytomegalovirus infection.

Do:

Wash your hands with soap and warm water often, especially:
After playing with children
After coming into contact with anyone’s, especially children’s, saliva or tears
Before touching your face (eyes, mouth, nose – where a virus could enter)
After using the restroom
After changing a diaper, using a tissue, etc.
Eat healthily and exercise during your pregnancy (keeps the immune system strong)
Use a condom each time you are sexually active to avoid exchanging fluids
Clean children’s toys and counters/handles that children often touch

Do not do it:

Have sexual contact, including kissing and any type of sex (especially unprotected), with new partners
Share drinks or utensils with others
Kiss children on the mouth
Basically, practicing general hygiene, avoiding new sexual partners, and limiting contact with children’s saliva, tears, etc. can help you avoid Cytomegalovirus.

Women who work in kindergartens or with children are more likely to become infected with cytomegalovirus. If this applies to you, talk to your doctor about your risk, wash your hands frequently, and avoid touching your face at work.

Cytomegalovirus and breastfeeding

You have probably heard how beneficial breastfeeding is. But what if you are afraid that the mother has some kind of disease, such as cytomegalovirus? As always, we recommend talking to your doctor if you know you had a primary cytomegalovirus infection during pregnancy and want to breastfeed.

If your baby is tested and confirmed for CMV, there should be no problem breastfeeding since you and the baby are already infected with the virus.

If you know you have or had a primary infection during pregnancy, you may have had a reactivation of the virus, or you are at high risk for cytomegalovirus infection, then you will need to get a test result from your baby and if it is negative, talk to your doctor before breastfeeding. You can also test your breast milk for live virus.

If your baby has CMV, it is safe to breastfeed since transmission has already occurred. Talking to your doctor will help you weigh the benefits and risks if your child does not have CMV.

What if my baby gets CMV from my breast milk?

As a rule, if a child becomes infected with cytomegalovirus through breast milk after birth, natural antibodies against cytomegalovirus are present in the child's body. They are passed from mother to child in utero (3rd trimester) or through breast milk. Most infants (and people of any age) infected with cytomegalovirus do not have symptoms and may be minors, if any.

When cytomegalovirus is passed to a baby through breast milk and/or other fluids after birth, it is called perinatal cytomegalovirus.

The greatest concern occurs when the baby is premature and not born with CMV. Premature babies should not receive a full dose of maternal antibodies during the 3rd trimester and are therefore less protected from cytomegalovirus in breast milk. The infant may develop more serious (but treatable and temporary) symptoms, such as:

enlarged or infected spleen or liver
sepsis-like syndrome (can lead to apnea, slow heart rate, or distended abdomen)
low platelet count
low white blood cell count
high liver enzyme amount

Although it sounds serious, most babies are able to recover spontaneously. Some may be treated with antiviral drugs such as ganciclovir or valganciclovir to help clear the infection. These drugs can have serious side effects, but your doctor can help you determine if the benefits outweigh the risks.