Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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Am Fam Physician. 2000;61(10):3073-3074

See related articleon prenatal respiratory viruses.

What is a respiratory viral infection?

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

  • Chickenpox

  • Fifth disease

  • Cytomegalovirus

  • Rubella (also called German measles)

What if I'm exposed to a respiratory viral infection when I'm 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 woman doesn't get infected. Even if she does, most viruses won't hurt her baby. However, some viruses can cause miscarriage or birth defects in the baby.

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

Here are some questions your doctor may ask you:

  • Did you hold or kiss the child?

  • How long were you in contact with the child?

  • When did the child get sick?

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

What should I do if I'm exposed to chickenpox?

Chickenpox is highly contagious. It can be serious during pregnancy. Sometimes, chickenpox can cause birth defects. If you've had chickenpox in the past, then you can't get it again and your baby will be fine. If you didn't have chickenpox or if you're not sure, you should see your doctor right away. Your doctor will test your blood to see if you're immune.

Many people who don't remember having chickenpox are immune anyway. If your blood test shows that you're 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'm exposed to fifth disease?

Fifth disease is common in children. 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've been slapped. Adults who get fifth disease don't usually have the “slapped cheek” rash. They may have sore joints.

Fifth disease doesn't 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 the baby is still inside your uterus).

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

What if I'm exposed to cytomegalovirus?

Cytomegalovirus (say: si–toe–meg–ah-low–vi–russ) usually doesn't cause any symptoms, so you won't know if you have it. It's the most common infection that can be passed from the mother to the baby. Cytomegalovirus affects 1 of every 100 pregnant women. It can cause birth defects.

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

What if I'm exposed to rubella (German measles)?

Today, 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're immune to rubella. Women who are not immune to rubella should get the vaccine after the baby is born. It's even better to be tested before you get pregnant. That way, you can get the vaccine if you need it. If you're exposed to rubella when you're pregnant, you can have blood tests to be sure you're immune.

What if I'm exposed to influenza?

Influenza hardly ever causes birth defects. It can be more serious for you if you get the flu while you're pregnant. You might get very sick. If you'll 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 [“mono”] and bronchiolitis) don't 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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