Skip to main content

Why Pregnant Women Should Receive a Flu Shot

Influenza Flu Vaccine and Pregnancy

Cooler weather, falling leaves, coughs, and sneezes are all signs the dreaded flu season is here. Flu season in the United States runs between October and May and annual vaccinations protect against new strains.

The flu shot is safe and highly recommended for pregnant women, here’s why:

Catching influenza (the ‘flu’) can be very dangerous for pregnant woman as they are at greater risk of miscarriage and severe complications like pneumonia, preterm labor, and preterm birth.

Changes in your immune, heart, and lung functions during pregnancy increase chances of getting seriously ill from flu.

A flu vaccination in your third trimester also helps protect your baby until they are old enough to get vaccinated themselves at six months old.

The Centers for Disease Control and Prevention (CDC) recommends all pregnant women get a flu vaccination. 

Is it safe and are there side effects?

Maternal vaccines are very safe for you and your baby. Flu shots have been given to millions of pregnant women over several decades with a good safety record.

However, the nasal spray vaccination is not recommended for pregnant women. This is because the nasal spray (FluMist) contains a live virus, and the needle vaccination does not.

Multiple studies have shown women who have a flu shot do not have an increased risk of miscarriage, while contracting influenza while pregnant would be more likely to put the mother and baby at risk.

The flu shot may have some minor side effects, which are no more likely for pregnant women or babies than they are for other individuals. Side effects may include headaches, aches, pains, or a slight fever. 

Please notify your provider if you’re prone to dizziness or fainting from injections or seeing needles.

What is thimerosal?

Some flu vaccines contain a mercury-based preservative, thimerosal, to prevent bacteria growth. It has been used in vaccines for over 70 years.

Most studies have shown the small amount of thimerosal in vaccines does not cause harm to an expecting mother or her baby and does not increase the risk of autism. 

Some people may have a rare allergy to thimerosal and may experience redness at the injection site. There is a thimerosal-free flu vaccine available for people who want to avoid thimerosal.

Breastfeeding moms and the flu shot

Mothers could pass the flu to their baby from breastfeeding, so a flu shot administered while breastfeeding will help protect both mother and child until the baby is old enough to have their own shot at six months old.


If you would like to meet with a knowledgeable doctor, consider contacting Women’s Health Arizona. As Arizona’s largest ObGyn group, we’re trained and solely dedicated to delivering the best ObGyn experience in convenient and comfortable settings around Phoenix.

Sign Up for Our Newsletter