This sheet is about exposure to the flu shot in 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 women 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 women 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 known as the “flu shot”. It is an inactivated vaccine. Inactivated means the shot does not contain live flu virus; so the vaccine cannot cause you to get the flu.
The influenza vaccine is updated every year to protect against the flu strains expected to be common that season. It is best to get the flu shot each year to stay protected against the flu strains currently active.
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 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 women 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 during 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 women 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.
I just got the flu shot. 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 is common and can occur in any pregnancy for many different reasons. Multiple studies have shown that women who have received the flu shot during pregnancy do not have an increased 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 research studies 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 the flu shot has been given in pregnancy since the 1960s. In studies of thousands of women from around the world who have received the injected flu shot just before or during pregnancy, no increased chance of birth defects has been seen.
Does getting the flu shot in pregnancy increase the chance of other pregnancy-related problems?
Studies have not found a higher chance of 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 exposed to the flu shot during pregnancy.
Breastfeeding while getting the flu vaccine:
Major medical groups note that women who are breastfeeding can receive the flu shot or nasal spray vaccine. Talk to your healthcare providers about all your breastfeeding questions.
If a man gets the flu shot, 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 a man’s fertility (ability to get a woman pregnant) or increase the chance of birth defects above the background risk. In general, exposures that men 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?
Women who are pregnant can be in close contact with others who have gotten the nasal spray vaccine.
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