The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What is cytomegalovirus infection during pregnancy?

Cytomegalovirus (CMV) is a virus that commonly infects people of all ages. Many people carry the virus without being sick. In healthy people, the immune system keeps the virus in check, usually with no symptoms. However, the virus remains in some kind of “sleeping state” called dormancy and, when a persons immune system weakens, it can become active, making the person very ill. Notoriously, this happens after infection with the human immunodeficiency virus (HIV) develops into acquired immunodeficiency syndrome (AIDS). However, even in healthy people, including in pregnant women, CMV can cause a type of hepatitis (inflammation of the liver), or a type of mononucleosis (mono), an infection that typically produces fever, sore throat, swollen glands, and fatigue. In people whose immune systems are very weak, CMV also can cause problems in various other organs, including the lungs and eyes, and much of the gastrointestinal tract.

How common is CMV during pregnancy?

Almost one-third of children in the United States become infected with CMV by 5 years of age and, by age 40, one-half of all people are infected. Generally, CMV infection is more common in lower socioeconomic groups, including women who are poor and pregnant. Its important to note that being infected does not mean being ill. A woman is considered to have been exposed to the virus, and therefore that the virus is within her if her blood is shown to produce antibodies against CMV. This is called being “seropositive for the virus.” Most women who are seropositive for CMV do not become ill during pregnancy, but they may have roughly a 22 percent chance of passing the virus to their neonates.

How is CMV during pregnancy diagnosed?

Maternal CMV infection is diagnosed by way of antibody tests performed on a sample of the mothers blood. Exposure of the baby to the virus can be detected by prenatal testing of amniotic fluid drawn from the mothers womb at around 20 to 21 weeks into the pregnancy.

Does CMV cause problems during pregnancy?

While you are pregnant, you can be infected with CMV either because the virus was there and dormant prior to you becoming pregnant or as a result of being infected after the pregnancy began. As in non-pregnant people, a CMV infection during pregnancy can have a range of effects, from no symptoms at all through varying severities of fever, sore throat, swollen glands, and fatigue, plus it can affect the liver, lungs, and other organs in some cases.

Does CMV during pregnancy cause problems for the baby?

CMV in a pregnant mother can infect the developing baby. Known as congenital CMV infection, this is much more likely in pregnant women who have become infected with CMV for the first time during pregnancy than in women who have been re-infected with CMV after many years. If congenital CMV infection develops, it can lead to problems in the lungs, brain, spleen, and liver, retarded growth in the womb, premature birth, and very low birth weight. The most common complication of congenital CMV infection is loss of hearing, affecting about 60 percent of newborns with congenital CMV, and beginning either at birth or anytime during childhood. Also, about 4 percent of fetuses with congenital CMV die in the womb.

What to consider about taking medications when you are pregnant or breastfeeding:

  • Any risks to yourself and your baby if you do not treat CMV.
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat CMV during pregnancy?

The antiviral drugs acyclovir and valacyclovir are available to treat very severe cases of CMV infection; however, this is usually not necessary in pregnant women. More often, valacyclovir is used to treat a newborn infant with congenital CMV. It is also used to treat cases of congenital CMV during the pregnancy so, in this case, doctors want the drug to reach the fetus.

Who should NOT stop taking medication for CMV during pregnancy?

If you are offered an antiviral drug, you should take it because the disease is far more dangerous than the drug. If the developing baby is infected, then the goal of the treatment is actually for him or her to be exposed to the drug. Furthermore, acetaminophen and paracetamol to treat the fever that can result from CMV are thought to be safe during pregnancy.

What should I know about choosing a medication for CMV during pregnancy?

You may find Pregistrys expert reports about the individual medications to treat CMV here. Additional information can also be found in the sources listed below.

What should I know about taking a medication for my CMV when I am breastfeeding?

First of all, you should know that CMV is transferred from person to person via body fluids, and that breastmilk is a body fluid. If you have an active CMV infection, you should not breastfeed if you do NOT treat the infection. Acyclovir, the antiviral drug that is given for severe cases of CMV, is considered safe during breastfeeding. Furthermore, acetaminophen and paracetamol are thought to be relatively safe to the babies of mothers who breastfeed.

What alternative therapies besides medications can I use to treat my CMV during pregnancy?

Mild cases and cases of CMV with no symptoms at all do not require medication nor any treatment, as long as the fetus is not infected.

What can I do for myself and my baby when I have CMV during pregnancy?

Talk to your healthcare providers in order to minimize the risks of CMV infection to yourself and your child.

Resources for CMV in pregnancy:

For more information about CMV during and after pregnancy, contact (800-994-9662 [TDD: 888-220-5446]) or read the following articles:


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General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.

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