The Seasonal Influenza Vaccine and Pregnancy: Separating Flu Shot Fact from Fiction

Flu Shot PreparationsBoth the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) recommend that pregnant women receive the inactivated seasonal influenza vaccine at the beginning of each flu season. In an inactivated vaccine, the virus within the vaccine is dead and no longer infectious. Pregnant women are advised against receiving an attenuated, or live, vaccine because of the potential risk of infection from the weakened but still live virus. When I was pregnant with my daughter last fall, I got my flu shot just as I do every year. The risks associated with the flu during pregnancy far outweigh any theoretical risks associated with the flu shot. Furthermore, the benefits of the seasonal flu shot far outweigh any theoretical risks associated with the vaccine.

When I recently posted about taking my family to get our flu shots for the year, I again mentioned that WHO and the CDC advise pregnant women to be vaccinated against seasonal influenza. As expected, I received some comments on my post from some readers who disagree with me. For example, one commenter wrote:

“Most flu manufacturers, in the vaccine’s manufacturers inserts, state that the effectiveness and safety of their vaccine has not been tested in pregnant women. Some even go on to state that pregnant women should NOT get their flu vaccine unless it is absolutely necessary. You can find this info on the first or sometimes 2nd page of each flu manufacture’s insert. Yet, the CDC, OB/GYNs and various marketing pieces state that pregnant women should get the vaccine. In my opinion, if the people that made & tested the vaccines say they don’t know if its safe for pregnant women to take it, then it’s pretty risky to tell this group to get it.”

In response, I stated:

“Pregnant women are at high risk for complications from the flu. The benefits of the flu shot outweigh any theoretical risks. I had my flu shot while pregnant and encourage other pregnant women to do the same.”

My response was followed by another comment from the original reader:

“How can you say the risks of getting the flu outweigh the risks of the vaccine for pregnant women when it has not been tested on pregnant women? We don’t even know the risks! The people that make the vaccine say not to take it if you are pregnant unless absolutely necessary.”

First, the potential complications from the flu are much worse for pregnant women than for the average healthy individual. As the March of Dimes explains, one of the ways in which pregnancy affects the body is to lower the response of the immune system. To prevent the body from rejecting the pregnancy, the immune system essentially weakens. Although great for not attacking and killing a growing fetus, a weakened immune system increases the likelihood of contracting a potentially harmful illness like the flu. Additionally, the heart and the lungs both work harder during pregnancy simply because of the changes to the body that occur as a baby grows and develops. Already stressed organs have a more difficult time recovering from an infection such as seasonal influenza, thus increasing the risk for debilitating or even fatal complications.

If a woman gets the flu while pregnant, her chances of experiencing complications are increased. For the average healthy individual, complications of the flu include pneumonia, bronchitis, and sinus and ear infections as well as other lung and heart problems. The seasonal flu can also result in death. According to the CDC, between 1976 and 2007, estimates of flu-associated deaths in the United States range from a low of about 3,000 to a high of about 49,000 people. Among pregnant women, the flu can cause miscarriage, stillbirth, premature birth, and birth defects as well as maternal death. In other words, the flu is bad news for a pregnant woman.

Second, although some fearmongers claim that the flu vaccine causes an increased rate of miscarriage and stillbirth among pregnant women, a study that looked at the complications associated with the flu shot discovered the opposite. In the study entitled “Adverse events in pregnant women following administration of trivalent inactivated influenza vaccine and live attenuated influenza vaccine in the Vaccine Adverse Event Reporting System, 1990-2009” as published in the American Journal of Obstetrics & Gynecology, the researchers searched the Vaccine Adverse Event Reporting System (VAERS) for reports of adverse reactions to either the inactivated flu vaccine or the attenuated flu vaccine between 1990 and 2009.

Between the years in question, the researchers discovered 175 reports of possibly vaccine-related medical complications among pregnant women in VAERS, a number that amounts to an estimated rate of 12.5 reported complications per one million pregnant women vaccinated against the flu. Of the reported complications, most were minor. Furthermore, although some miscarriages and stillbirths were reported, the rate of 1.9 miscarriages per million pregnant women vaccinated was substantially lower than the average rates of miscarriage in the general population. In other words, the flu shot does not increase the risk of miscarriage or stillbirth among pregnant women. Additionally, because the seasonal flu does increase the risk of miscarriage and stillbirth, getting the flu shot decreases the risk of fetal death from the flu.

Set the conspiracy theories aside. The seasonal flu shot is safe during pregnancy. If you are an expectant mama-to-be, protect yourself and your baby by getting a seasonal influenza vaccine.


Adverse events in pregnant women following administration of trivalent inactivated influenza vaccine and live attenuated influenza vaccine in the Vaccine Adverse Event Reporting System, 1990-2009:
Flu and pregnancy:
Flu shots safe for pregnant women, study finds:
Flu symptoms & severity:
Pregnant women & influenza (flu):

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