In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. This sheet talks about whether exposure to seasonal influenza may increase the risk for birth defects over that background risk. This information should not take the place of medical care and advice from your health care provider.

What is influenza?

Influenza is an infection of the respiratory (breathing) tract. It is often called the flu. The symptoms of influenza are fever, headache, chills, muscle aches, coughing, congestion, runny nose, and sore throat. Influenza sometimes causes vomiting and diarrhea.

The typical flu season is from October through May of each year, and usually has the most activity in February. The types (strains) of viruses that cause seasonal influenza change a little bit each year. Starting during the 2009-2010 flu season, people got sick from both seasonal influenza viruses and a new type of virus called H1N1.

Is influenza contagious? How does the virus spread?

Yes, influenza is contagious. The virus is spread through contact with respiratory droplets from the nose and mouth of infected individuals. When people cough, sneeze, or talk droplets containing the virus are spread through the air. The incubation period (the time between exposure and the development of symptoms) is about 1 to 4 days. A person with the flu is contagious for up to a week after he or she first develops symptoms.

Can having influenza during pregnancy put my health at risk?

Yes. When you are pregnant your body has a harder time fighting infections. Pregnant women have an increased chance of developing serious complications from the flu, such as respiratory distress (severe breathing problems).

Can having influenza during pregnancy cause birth defects or put my baby at risk?

The influenza virus itself has not been shown to cause birth defects. However, having a high fever during early pregnancy might increase the chance for birth defects. Therefore, fever during pregnancy should be treated. Acetaminophen is the drug of choice for reducing fever during pregnancy. Tylenol® is one brand of acetaminophen. MotherToBaby has fact sheets on hyperthermia (fever) and acetaminophen (Tylenol®) at and

Being very sick from the flu may increase the chance of pregnancy complications such as pregnancy loss or premature delivery. It is important to talk with your health care provider if you are pregnant and have symptoms of the flu.

How can I protect myself and my baby?

The most important thing you can do for yourself and your baby is to get the injected seasonal influenza vaccine, also known as the flu shot. Because pregnant women are at an increased risk for complications from influenza, women who are pregnant (whether in their first, second, or third trimester), or planning to become pregnant, should get the seasonal flu shot.

A nasal-spray influenza vaccine (FluMist®) is also available. This vaccine contains a live but weakened virus. The nasal-spray influenza vaccine is not recommended during pregnancy.

For more information about the flu vaccines during pregnancy, see the MotherToBaby fact sheet Seasonal Influenza Vaccine (Flu Shot) during Pregnancy at

In addition to getting the flu shot, be sure that you and others around you are doing the following to help prevent spread of the flu:

  • Wash your hands with soap and water frequently.
  • Avoid touching your eyes, nose, or mouth.
  • Try to avoid close contact with sick people.
  • Cover your nose and mouth when you cough or sneeze.
  • Stay home and avoid close contact with others if you are sick.

What should I do if I get sick?

If you have flu-like symptoms, call your health care provider right away. Your health care provider may recommend antiviral medications to lessen the symptoms of the flu and to reduce the chance of serious illness. These medications work best if taken early in the course of the illness. For more information about antiviral medications, see the MotherToBaby fact sheet Antiviral Medications to Treat/Prevent Influenza during Pregnancy at

If you are sick, stay home and avoid close contact with others to prevent passing the illness to other people. Be sure to drink plenty of fluids. Treat fever right away with acetaminophen (Tylenol®).

Should I talk to my health care provider if one of my family members is sick?

Yes. Talk with your health care provider if you have been in close contact with someone who has the flu. Your health care provider can help you decide whether taking an antiviral medication for flu prevention is appropriate for you.

Should I stop breastfeeding if I have the flu?

No. There are antibodies in your breast milk that may help prevent your baby from getting sick.

It is important to try to protect your baby from getting sick. Wash your hands with soap and water before holding your baby. Avoid coughing or sneezing on your baby. Consider wearing a mask over your nose and mouth while feeding and caring for your baby to help prevent you passing the illness to your baby. While you are ill, you may want to consider having a family member who is not sick help you with caring for your baby.

If your baby has the flu, it is especially important to breastfeed as often as possible. Your baby will need extra fluids during this time. Your milk is better for this than anything else, even than things like Pedialyte®. Also, antibodies in your milk help your baby fight the infection and get better faster. Be sure to talk to your health care provider about all your breastfeeding questions.

References Available By Request