This sheet is about exposure to the flu shot in a pregnancy and while breastfeeding. This information is based on available published literature. It should not take the place of medical care and advice from your healthcare provider.
What is influenza?
Influenza is commonly called the “flu.” It is an infection of the respiratory (breathing) tract. The symptoms of the flu are fever, headache, chills, muscle aches, cough, congestion (stuffy nose), runny nose, sore throat, and feeling tired (fatigue). The flu sometimes causes vomiting and diarrhea. The typical flu season is from October through May of each year, and usually has the most activity between December and February. The types (strains) of viruses that cause seasonal influenza can change each year.
Why is the flu a concern for people who are pregnant and for the pregnancy?
Even if you are healthy, the body can have a harder time fighting infections when pregnant. The flu can cause serious symptoms in people who are pregnant, such as respiratory distress (severe breathing problems) and even death. Being very sick from the flu can increase pregnancy complications, such as preterm delivery (delivery before 37 weeks of pregnancy). While having the flu during pregnancy does not appear to increase the chance of birth defects, symptoms of the flu, such as a high fever, could affect the fetus. For more information, see the MotherToBaby fact sheet on Seasonal Influenza (the Flu) at https://mothertobaby.org/fact-sheets/seasonal-influenza-the-flu-pregnancy/.
What is the seasonal influenza vaccine (flu shot)?
The injected seasonal influenza vaccine is commonly called the “flu shot”. It is an inactivated vaccine, meaning that the vaccine does not contain “live” flu virus and cannot cause you to get the flu. The influenza vaccine is updated every year to include the main flu strains expected to be going around in the upcoming flu season. It is best to get the flu shot each year to have up-to-date protection from the current flu strains.
Major medical groups recommend that people who are pregnant (whether in their first, second, or third trimester) get the flu shot.
A nasal spray flu vaccine may also be available; however, it is not recommended for use during pregnancy. Unlike the flu shot, the nasal spray vaccine contains a live, but weakened, flu virus (live attenuated influenza vaccine).
I just found out that I was pregnant when I got the nasal spray flu vaccine. Should I be concerned?
The nasal spray vaccine is a live attenuated vaccine (contains live but weakened flu virus). In general, it is suggested that people who are pregnant avoid live vaccines. However, if you accidentally get the nasal spray vaccine while pregnant, it is not expected to increase the chance of birth defects or pregnancy complications. Talk with your healthcare provider in the unlikely case you have any symptoms of the flu after receiving the nasal spray vaccine.
When should I get the flu shot?
To provide protection during the flu season, it is important to get the vaccine as soon as it is available. The vaccine usually becomes available in September and is offered throughout flu season. Protection begins about two weeks after you get the flu shot and lasts at least six to eight months. It is necessary to receive the seasonal flu shot each year to be protected in the current flu season.
My due date is only a couple weeks away. Do I still need to get the flu shot?
It is important to protect yourself from getting sick both during your pregnancy and after your baby is born. Getting vaccinated during pregnancy might also help protect your baby from getting sick during their first 6 months of life. This is important because infants less than 6 months of age cannot receive the flu vaccine. In general, September and October are good times to be vaccinated each year. Vaccination in July or August can be considered for people who are in the third trimester of pregnancy during those months. Talk with your healthcare provider about the best time for you to get the flu vaccine.
Is there anyone who should not receive the flu vaccine?
In the past, some people with allergies or hypersensitivities to eggs were told to avoid the flu vaccine, because most flu vaccines contained a small amount of egg protein. However, the Centers for Disease Control and Prevention (CDC) now states “People with egg allergy may receive any vaccine (egg-based or non-egg-based)” and recommends that everyone older than 6 months of age should get a flu shot every year. Studies that have looked at the use of both the nasal spray vaccine and flu shots in egg-allergic and non-egg-allergic patients suggest that severe allergic reactions in people with egg allergies are unlikely. There are also vaccines that do not contain egg protein. However, anyone with a severe, life-threatening allergy to any of the vaccine ingredients should talk with their healthcare provider about what vaccines are recommended.
I just got the flu vaccine. How long should I wait until I try to get pregnant?
There is no recommended waiting period since the flu shot can be given at any time during pregnancy.
If I get the flu shot, can it make it harder for me to get pregnant?
Studies have not been done to see if a flu shot would make it harder to get pregnant.
Does getting a flu shot increase the chance for miscarriage?
Miscarriage can occur in any pregnancy. The flu shot is not expected to increase the chance of miscarriage.
Does getting the flu shot increase the chance of birth defects?
Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. In the United States the flu shot has been given in pregnancy since the 1960s. Studies of thousands of people, from around the world, who have received the injected flu shot just before or during pregnancy have found no increased chance for birth defects. Major medical groups recommend that those who are pregnant (whether in their first, second, or third trimester) receive the flu shot.
Does getting the flu shot in pregnancy increase the chance of other pregnancy-related problems?
Studies have not found a higher chance for other pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth).
Does getting the flu shot in pregnancy affect future behavior or learning for the child?
Studies have not found an increased chance of negative effects on children who were exposed to the flu shot during pregnancy.
Breastfeeding while getting the flu vaccine:
Major medical groups note that persons who are breastfeeding can receive the flu shot or nasal spray vaccine. Talk to your healthcare providers about all of your breastfeeding questions.
If a male gets the flu vaccine, could it affect fertility or increase the chance of birth defects?
There is no evidence to suggest that the flu shot or nasal spray vaccine would affect fertility (ability to get partner pregnant) or increase the chance of birth defects above the background risk. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
One of my family members just got the nasal spray flu vaccine. Can I be around them while I am pregnant?
People who are pregnant can be in close contact with others who have gotten the nasal spray vaccine.
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OTIS/MotherToBaby encourages inclusive and person-centered language. While our name still contains a reference to mothers, we are updating our resources with more inclusive terms. Use of the term mother or maternal refers to a person who is pregnant. Use of the term father or paternal refers to a person who contributes sperm.