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Am Fam Physician. 2003;68(6):1171-1172

What is a viral respiratory infection?

A viral respiratory infection is a contagious illness that affects your respiratory tract (your breathing) and causes other symptoms. The flu and the common cold are examples of viral respiratory infections. Other examples of respiratory viruses are:

  • Chickenpox (also called varicella)

  • Fifth disease

  • Cytomegalovirus (say: “si-toe-meg-ah-low vi-russ”)

  • Rubella (also called German measles)

What if I am exposed to a viral respiratory infection while I am pregnant?

Pregnant women can be exposed to people with viral infections at work and at home. The infected person is usually a child. Most of the time, the pregnant woman does not get infected. Even if she does, most viruses will not hurt her baby. However, some viruses can cause a miscarriage or birth defects in the baby.

If you are exposed to chickenpox, fifth disease, cytomegalovirus, or rubella while you are pregnant, you should tell your doctor right away. Your doctor will want to know how much contact you had with the infected person.

Here are some questions your doctor may ask you:

  • Did you hold or kiss the infected person?

  • How long were you in contact with the infected person?

  • When did the infected person get sick?

  • Did a doctor diagnose the infected person's illness? Were any tests done?

What should I do if I am exposed to chickenpox?

Chickenpox is caused by the varicella virus and is highly contagious. It can be serious during pregnancy. Sometimes, chickenpox can cause birth defects. If you had chickenpox in the past, you cannot get it again, and your baby will be fine. If you did not ever have chickenpox or if you are not sure you had it, you should see your doctor right away. Your doctor will test your blood to see if you are immune.

Many people who do not remember having chickenpox are immune anyway. If your blood test shows that you are not immune, you can take medicines to make your illness less severe and possibly help protect your baby from chickenpox.

What should I do if I am exposed to fifth disease?

Fifth disease is common in children. One half of all adults are susceptible to fifth disease and can catch it from children.

Children with fifth disease can get a rash on their body. They may have red cheeks that look like they have been slapped. Adults who get fifth disease do not usually have the “slapped-cheek” rash. They may have sore joints.

Fifth disease does not cause birth defects, but it can cause anemia (low blood count) in your baby. If the anemia is bad, the baby could die. The anemia might get better by itself, or your baby might need to have a blood transfusion while still inside your uterus.

If you get fifth disease early in your pregnancy, you could have a miscarriage. If you are exposed to fifth disease, call your doctor. Your doctor may have you take a blood test to see if you are immune. You may also need an ultrasound exam to see if the baby has been infected.

What if I am exposed to cytomegalovirus?

Cytomegalovirus usually does not cause any symptoms, so you will not know if you have it. It is the most common infection that can be passed from a mother to her baby. Cytomegalovirus affects one of every 100 pregnant women. It can cause birth defects.

It is important to prevent cytomegalovirus infection because there is no way to treat it. Women who work in day care centers and in a health care setting have the highest risk of getting infected. Pregnant women with these jobs should wash their hands after handling diapers and avoid kissing and nuzzling the babies. If you think you have been exposed to a person who has cytomegalovirus, you should see your doctor right away.

What if I am exposed to rubella (German measles)?

Rubella is rare. Since 1969, almost all children have had the rubella vaccine. Rubella used to be a common cause of birth defects. At the first prenatal visit, all pregnant women should be tested to see if they are immune to rubella. Women who are not immune to rubella should get the vaccine after the baby is born. It is better to be tested even before you get pregnant. That way, you can get the vaccine before you get pregnant. If you are exposed to rubella when you are pregnant, you can have blood tests to be sure you are immune.

What if I am exposed to influenza?

Influenza hardly ever causes birth defects. It can be more serious for you if you get the flu while you are pregnant. You might get very sick. If you will be pregnant during the flu season (from October through March), you should get a flu shot in the fall.

What about other viral infections?

Most other respiratory viruses (such as regular measles, mumps, roseola, mononucleosis [often called “mono”] and bronchiolitis) do not seem to increase the normal risk for birth defects. In normal pregnancies, the risk of serious birth defects is only 2 to 3 percent.

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