Seasonal Influenza Vaccine (Flu Shot)

Last Update: 02 Apr 2025

Medication

Table of content

1. What is it? 2. What are the risks? 3. Breastfeeding/ chestfeeding 4. Fathers and sperm donors 5. Other family members 6. Key points

Welcome to our fact sheet on seasonal influenza vaccine (flu shot) during pregnancy and breastfeeding/ chestfeeding. The information given is based on recent research and may change as science progresses. Please remember that this content does not replace personalized advice from your healthcare team.

The HEALTHY PREGNANCY HUB team is collaborating with MotherToBaby to share information on this topic. The original version is available here (July 2024).

Serene, our chatbot, can also answer your questions about medications during pregnancy.

Please note that this fact sheet is based on United States information and has been adapted for Canada, with a review by our Canadian experts. Minor differences may exist between the two countries. Always consult your healthcare professional for information tailored to your situation.

1. What is it?

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 individuals 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 pregnant individuals, 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 our fact sheet on Seasonal Influenza (the Flu) here. 

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 pregnant individuals (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 pregnant individuals 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 individuals 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.

Do you know how to stay protected against the flu during your pregnancy?

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2. What are the risks according to research?

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 individuals 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 individuals 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.

3. Breastfeeding/ chestfeeding while getting the flu vaccine

Major medical groups note that individuals who are breastfeeding/ chestfeeding can receive the flu shot or nasal spray vaccine. Talk to your healthcare providers about all your breastfeeding/ chestfeeding questions.

4. Fathers and sperm donors

If a male 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 male’s fertility (ability to get a partner pregnant) or increase the chance of birth defects above the background risk. In general, exposures that fathers and sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures here. 

5. Other family members

One of my family members just got the nasal spray flu vaccine. Can I be around them while I am pregnant?

Pregnant individuals can be in close contact with others who have gotten the nasal spray vaccine.

Key points

Influenza (the flu) is a respiratory infection that can cause serious complications during pregnancy, such as respiratory distress and preterm birth.
The injectable flu vaccine is recommended every year during pregnancy to protect both the pregnant individual and the baby from seasonal flu strains.
The nasal spray flu vaccine is not recommended during pregnancy, but if given by accident, it does not increase the risk of complications.
The flu vaccine has been given to pregnant individuals since the 1960s. Studies have not found any increased risk of miscarriage, birth defects, pregnancy complications, or long-term learning or behavioral issues in the child.
People who are breastfeeding can safely receive the flu vaccine.
There is no evidence that the injectable seasonal flu vaccine or the nasal spray flu vaccine affects male fertility or increases the risk of birth defects beyond the background risk.
If you have specific questions about the flu vaccine, talk to your healthcare provider.

References

Please click here for references.

Disclaimer

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