How the Flu Affects Pregnant Women

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Influenza is a potentially serious, contagious respiratory illness that can lead to complications for pregnant women and their unborn children. According to the Centers for Disease Control and Prevention (CDC), the flu is more likely to cause severe illness in pregnant women than in women of reproductive age who are not pregnant. 

During pregnancy, a woman's body undergoes many changes, including those to the immune system, heart, and lungs. These make pregnant women more susceptible to more severe symptoms and complications from influenza that may require hospitalization.

Flu symptoms come on suddenly and typically include headache, fever, congestion, and body aches. If you are pregnant and suspect you may have the flu, it is important to see your doctor for testing and treatment as soon as possible.

pregnant woman having a headache and morning sickness
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Pregnancy and Immunity

The fetal-maternal immune interaction is complex. The immune system—the body’s defense against foreign invaders—changes during pregnancy. Under normal immune conditions, a fetus would be viewed as a foreign invader and attacked. Instead, a mother's immune response is altered to protect the unborn child. 

At the same time, the immune system goes into overdrive to support two people. This can result in it not working as effectively, making pregnant women more susceptible to certain infections. 

Hormonal fluctuations can also play a role in reduced immunity. Progesterone, for example, causes fluid retention. During pregnancy, excess fluid in the lungs can raise a woman's risk of pneumonia and other lung infections. 

In addition, as the baby grows larger, more pressure is put on the mother's abdomen. This makes it harder to breathe and clear the lungs, which can hinder the lung’s ability to resist infection.

Possible Complications

While most women who get the flu during pregnancy can weather it without consequence, others aren’t so lucky. Influenza can be serious and may lead to complications and even death for both mother and child. The earlier it is reconized and treated, the better.

Research shows that women are four times more likely to be hospitalized due to flu complications during pregnancy with rates similar to those ages 65 and older. The risk is highest in later stages of pregnancy, with women in the first trimester at a lower risk of respiratory complications. 

Influenza can also increase the risk of pregnancy complications including preterm labor, miscarriage, and stillbirth. Risks to the baby include premature birth, low birth weight, born small for gestation age, and lower Apgar scores, as well as birth defects.

Fever, a common flu symptom, is associated with neural tube defects.


The influenza virus is highly contagious and spreads through contact with infected respiratory droplets in the air or on surfaces. The CDC highly recommends pregnant women and women who may become pregnant get vaccinated against influenza.

The annual influenza vaccine has been proven safe for pregnant women and their unborn children in numerous studies. (Note: The flu shot is approved in pregnant women, though the nasal flu vaccine is not.)

In fact, a study of over 2 million pregnant women worldwide found the vaccine reduced a pregnant woman’s risk of being hospitalized from flu by an average of 40%. The study determined the flu shot offers equal protection throughout all three trimesters.

In addition to being critical to prenatal health, the flu shot can even provide protection from the flu for the child for up to six months after birth. This is great news since infants under 6 months old cannot get a flu shot.

Other ways to protect yourself and your unborn child against the flu include:

  • Wash your hands: The influenza virus can live on surfaces for up to 48 hours. Get in the practice of washing your hands for at least 20 seconds after touching public surfaces or sharing a space with someone who is ill. Alcohol-based hand sanitizers can be used to kill germs on the go.
  • Don't touch your face: The influenza virus is often spread when a person touches a contaminated surface, then touches their eyes, nose, or mouth.
  • Disinfect surfaces: Clean and disinfect frequently touched surfaces in your home, work, or school, especially when someone is ill. The flu virus can be killed by heat above 167 degrees F and by cleaning products including chlorine, hydrogen peroxide, detergents, iodine-based antiseptics, and alcohol.
  • Keep your distance: During an influenza outbreak, avoid crowded places and stay away from people who are sick.
  • Take care of yourself: Get plenty of sleep, be physically active, manage your stress, drink plenty of fluids, and eat nutritious food to keep your immune system strong.


Due to the increased risk of complications from influenza, the CDC recommends that pregnant women who contract the flu be promptly treated with antiviral medications. Starting treatment within 48 hours of symptom onset is shown to shorten the duration of illness and reduce the severity of symptoms.

In addition to antiviral medications, pregnant women can take Tylenol (acetaminophen) to treat symptoms. Since fever can pose a risk to the fetus, it is important to treat flu-related fevers during pregnancy.

Due to possible maternal complications, it is important to monitor your condition and contact your doctor with any questions. Pay close attention to your respiration: If you experience any difficulty breathing, seek medical attention right away. If you aren't getting enough oxygen, the baby probably isn't either. If you think you might be wheezing or your chest feels tight, call your doctor or go to the emergency room.

When to Seek Emergency Care

If you are pregnant and experience any of the following, call 911 or seek emergency medical attention immediately.

  • Shortness of breath or difficulty breathing
  • Confusion
  • Sudden dizziness
  • Pain in the chest or abdomen
  • Severe vomiting or vomiting that won't stop
  • High fever that does not go respond to fever-reducing medication
  • Decreased movement of the baby

A Word From Verywell

It's natural to be concerned about every little thing when you're pregnant. While some issues may warrant little concern, a potential case of the flu is very worthy of your attention—even if it ends up only being an abundance of caution. If you're ever in doubt about what to do, contact your obstetrician.

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