Why the Flu Shot for Pregnant Women Matters

The benefits of getting a flu shot during pregnancy go beyond avoiding the miserable flu

When you’re pregnant, taking care of your health means also taking care of the health of your baby. And getting the flu shot is one of the simplest — and most effective — ways to protect both of you from flu-related complications.

Pregnancy puts additional demands on your body and can change the way your immune system, heart and lungs work. That’s why pregnant women are more vulnerable to serious illness from influenza (flu).

“Every year, the flu poses serious health risks, especially for pregnant women and their babies,” says Diane Timms, DO, a Geisinger maternal-fetal medicine specialist. “Getting vaccinated can lower your risk of getting the flu, help prevent severe illness and complications, and pass on protective antibodies to your baby — before and after birth.”

Why the flu during pregnancy is more serious

Flu during pregnancy is more likely to cause serious illness — and can be dangerous to your developing baby.

Your body is working overtime to support your growing baby. During pregnancy, changes to your immune system can make it harder to fight respiratory infections like influenza. Your heart and lungs are also working harder to meet the increased demands of pregnancy. Together, these changes can make flu symptoms more severe and recovery more difficult.

“Even healthy women can become very ill with influenza while pregnant,” says Dr. Timms. “When severe flu strikes, it can lead to high fever, dehydration, sinus and ear infections, pneumonia and even hospitalization.”

Flu during pregnancy also has been linked to complications, such as preterm birth, low birth weight and, in rare cases, pregnancy loss. High fever early in pregnancy can be a particular concern.

The benefits of the flu shot during pregnancy are clear: Getting vaccinated makes these outcomes less likely for both you and your baby.

How the flu shot during pregnancy protects you and your baby

The American College of Obstetricians and Gynecologists recommends that women who are pregnant during flu season get a flu shot no matter what trimester they’re in.

The flu shot teaches your immune system to recognize and fight the influenza viruses included in the vaccine, boosting your immune response. During pregnancy, vaccination can help:

Lower your risk of catching the flu
Reduce your risk of severe illness — and flu-related complications — if you do get sick
Lower the risk of certain pregnancy complications
Pass protective antibodies to your baby before birth

Research shows that flu vaccination during pregnancy can reduce the risk of hospitalization from flu by about 40% — and may also reduce risk of infant hospitalization by 48%.

There’s another important benefit of getting the flu shot during pregnancy: Some of the antibodies your body makes to help fight influenza cross the placenta to reach your baby. They can help protect your newborn during the first few months of life — a time when babies are too young to receive their own flu vaccine. If you breastfeed, antibodies in breast milk can provide added support for your baby’s immune system.

“Your baby can receive their first flu vaccine at 6 months of age,” says Dr. Timms. “Until then, your vaccination during pregnancy can provide an important layer of protection during a vulnerable period when infants face higher risks from flu complications.”

Is the flu shot safe during pregnancy?

The flu shot has a strong safety record during pregnancy. Large studies and ongoing monitoring by the CDC have found that inactivated flu vaccines (containing dead virus components) are safe in any trimester — first, second or third. Research has not found an increased risk of miscarriage, birth defects, stillbirth, preterm birth or other adverse pregnancy outcomes associated with the inactivated flu shot.

“The flu shot given during pregnancy is an inactivated vaccine — meaning it cannot cause influenza infection,” says Dr. Timms. “Flu shots have been given to millions of people over many years with an excellent safety record.”

When you get vaccinated, just be sure to ask for the flu shot and not the nasal spray vaccine. The nasal spray contains live attenuated (weakened) virus and isn’t recommended during pregnancy.

Most side effects from the flu shot are mild and brief — and signs your immune system is responding. You might notice soreness, redness or swelling where the shot was given, or a low-grade fever, headache, muscle aches or fatigue. These typically improve within a day or so. Severe allergic reactions are rare.

If you’re concerned about allergies or other risks, talk to your doctor before getting vaccinated.

When should pregnant women get the flu shot?

For the best protection, get your flu shot in early fall like September or October, before the start of flu season — which typically begins in October and can last until May.

It takes about 2 weeks after vaccination for your body to develop protective antibodies, so getting vaccinated before flu activity increases can give you a head start on protection.

“Vaccination in any trimester is safe and beneficial,” says Dr. Timms. “Even if you get pregnant later in flu season and haven’t been vaccinated, it’s still recommended to get the flu shot during pregnancy.”

And don’t skip vaccination if you’ve already had the flu. Several strains can circulate in a single season. The flu shot for pregnant women can help protect against different strains and may lessen the severity if you get sick again.

“The flu shot is an important part of prenatal care,” says Dr. Timms. “The sooner you’re vaccinated, the sooner you and your baby can benefit from that protection.”