This sheet is about exposure to the flu shot in a pregnancy and while breastfeeding. This information 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 developing baby?
Even if you are healthy, the body has a harder time fighting infections when you are 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 while pregnant does not appear to cause birth defects, symptoms of the flu, such as a high fever, could affect the developing baby. 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 flu vaccine?
The injected seasonal influenza vaccine (flu shot) is a noninfectious vaccine. This means that the shot cannot cause you to get the flu. The mixture of killed viruses in the flu shot is updated every year to include the main strains expected to be circulating in the upcoming flu season. It is necessary to receive the flu shot each year in order to have up-to-date protection from the current flu strains. Major medical groups recommend that those who are pregnant (whether in their first, second, or third trimester) get the seasonal flu shot given by injection.
A nasal-spray influenza vaccine may also be available. However, the nasal-spray form is not recommended for use during pregnancy. Unlike the flu shot, this 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 contains a weakened active virus (“live vaccine”). In general, those who are pregnant are advised to avoid live vaccines. However, if you accidentally get the nasal spray vaccine while pregnant, this is not expected to increase the chance of having a baby with a birth defect or other pregnancy complications. See your healthcare provider in the unlikely case you have any symptoms of the flu.
When should I get the flu shot vaccine?
To provide protection during the flu season, it is important to get the vaccine as soon as it becomes 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 your pregnancy may also help protect your baby from getting sick during the first 6 months of life. This is especially important because infants less than 6 months of age cannot receive 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. This is because most flu vaccines contain a small amount of egg protein. Newer recommendations state that everyone older than six months of age should receive a flu shot. This is because there are vaccines that do not contain egg protein. Also, the vaccines with egg have such a tiny amount of egg protein that an allergic reaction isn’t likely to happen in response to vaccination. However, anyone with a severe, life-threatening allergy to any of the vaccine ingredients should discuss the vaccine with their healthcare provider first.
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. Based on the studies reviewed, 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 to later affect the child when the pregnant person receives a flu shot during pregnancy.
Can I get the flu vaccine while breastfeeding?
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. The Centers for Disease Control and Prevention (CDC) has more information here: https://www.cdc.gov/breastfeeding/breastfeeding-special-circumstances/maternal-or-infant-illnesses/influenza.html.
If a male gets the flu vaccine, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects?
There is no evidence to suggest that the flu shot or nasal spray affect the sperm or transmits flu to the developing baby through the semen. In general, exposures that fathers or sperm donors have are unlikely to increase the 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 recognizes that not all people identify as “men” or “women.” When using the term “mother,” we mean the source of the egg and/or uterus and by “father,” we mean the source of the sperm, regardless of the person’s gender identity.
