This sheet is about exposure to the flu shot in pregnancy and while breastfeeding. This information is based on research studies. 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. 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 lasts from October through May of each year, with most cases of flu happening between December and February. The types (strains) of viruses that cause seasonal influenza can change from year to year.
Why is the flu a concern during pregnancy?
Even in healthy people, the body can have a harder time fighting infections during pregnancy. The flu can cause serious problems in women who are pregnant, such as respiratory distress (severe breathing problems) and even death. Being very sick from the flu can also increase the chance of pregnancy complications, such as preterm delivery (birth before week 37). While having the flu during pregnancy does not appear to increase the chance of birth defects, some 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 seasonal influenza vaccine lowers the chance of getting the flu or getting very sick from the flu. The vaccine is updated every year to protect against the flu strains that are expected to be common that season. It is necessary to get the influenza vaccine (flu shot) each year in order to stay protected against the flu strains that are currently active.
The injected seasonal influenza vaccine is commonly known as the “flu shot”. The flu shot is an inactivated vaccine, which means it does not contain live flu virus. The flu shot cannot cause you to get the flu. Major medical groups recommend that women who are pregnant (whether in their first, second, or third trimester) get the flu shot.
A nasal spray flu vaccine might also be available, but 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 got the nasal spray flu vaccine before I knew I was pregnant. Should I be concerned?
The nasal spray flu vaccine is a live attenuated vaccine (contains live but weakened flu virus). In general, it is suggested that women avoid live vaccines during pregnancy. However, accidentally getting the nasal spray vaccine while pregnant is not expected to increase the chance of birth defects or pregnancy complications. Talk with your healthcare provider in the unlikely case that you have any symptoms of the flu after receiving the nasal spray vaccine.
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 flu vaccine.
When should I get the flu shot?
The flu shot usually becomes available in September and is offered throughout flu season. Protection begins about 2 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 during flu season.
In general, September and October are good times to get the flu shot each year. Getting it 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 shot.
I am pregnant and 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 the flu shot lowers the chance of getting sick and passing influenza to your baby. Getting vaccinated during pregnancy can also pass antibodies (protection) to the baby to help protect them from getting the flu during their first 6 months of life. This is important because infants cannot receive their own flu vaccine until 6 months of age.
I just got the flu shot. How long should I wait before trying to get pregnant?
There is no recommended waiting period before trying to get pregnant. The flu shot can be given at any time before or during pregnancy.
Can getting the flu shot make it harder for me to get pregnant?
Studies have not been done to see if getting the flu shot can make it harder to get pregnant.
Does getting a flu shot increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Studies have shown that getting the flu shot during pregnancy does not increase the chance of miscarriage.
Does getting the flu shot increase the chance of birth defects?
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at published data to try to understand if an exposure, like the flu shot, might increase the chance of birth defects in a pregnancy. In the United States (U.S.), the flu shot has been given in pregnancy since the 1960s. Studies of thousands of people in the U.S. and around the world who have received the flu shot just before or during pregnancy have not found an increased chance of birth defects.
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) after getting the flu shot during pregnancy.
Does getting the flu shot in pregnancy affect future behavior or learning for the child?
Studies have not found an increased chance of behavior or learning issues for the child after getting the flu shot during pregnancy.
Breastfeeding after getting the flu vaccine:
Major medical groups state that women who are breastfeeding can receive the flu shot or nasal spray influenza vaccine. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a man gets the flu shot, could it affect his fertility or increase the chance of birth defects?
There is no evidence that getting the flu shot or nasal spray influenza vaccine would affect a man’s fertility (ability to get partner pregnant) or increase the chance of birth defects. When everyone who is around the baby after delivery is vaccinated against the flu, it helps protect the baby from being exposed to the flu virus. 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/.
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