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Flu Shot and Pregnancy

young nurse with hypodermic needle

Wondering about the safety of the flu shot and pregnancy? If you're pregnant and it's flu season, what should you do?

What's in the Flu Shot?

The flu shot is made with the inactivated flu virus. The inactivated virus is a virus that has been killed, so it can no longer cause the flu. The body reacts to the shot by creating antibodies, which are special proteins that can fight the flu. If you're exposed to the flu later on, your body is prepared to fight the virus off before it makes you sick.

You can't get the flu from a flu shot. Only live flu virus can cause the flu.

Pregnancy and the Flu

Getting the flu is never any fun. But, when you're pregnant, the flu is both uncomfortable and dangerous.

Pregnant women are more likely than non-pregnant women to get so sick from the flu that they need to be hospitalized. Even if there are no serious complications, symptoms often last longer in pregnant women.

The U.S. Advisory Committee on Immunization Practices recommends that pregnant women receive the flu shot if they'll be pregnant during flu season from late November through March.

Flu Shot and Pregnancy Timing

Three separate studies of the flu shot and pregnancy showed no adverse affects on either the mother or the fetus. Some doctors feel that it's safe to give the shot any time during pregnancy, but others prefer to wait until after the first trimester. Talk with your own doctor to find out what he or she recommends.

Thimerosal (Mercury)

Most preparations of the flu shot contain a preservative called thimerosal. Thimerosal contains tiny amounts of mercury. Some people think that thimerosal can cause neurological problems in children, such as autism or attention deficit disorder (ADD).

As of early 2007, medical studies showed no association with autism. One study showed a weak connection with ADD, but others showed no connection at all. However, as a precaution, thimerosal has been removed from most vaccines for children.

A large study of pregnant woman showed no adverse effects on the fetus from flu shots containing thimerosal. Still, if you're concerned, ask your doctor to order a thimerosal-free shot for you.

You can learn more about thimerosal, the flu shot and pregnancy at the Thimorosal page at the Centers for Disease Control.

Flu Shot Effectiveness

How well the flu shot works depends on two things:

  • First, your own immune system has to react to the shot and make flu antibodies. For most healthy, young people, this is not a problem.
  • Second, the strain of flu that's going around has to be similar to the one used in the flu shot. Medical scientists look at patterns of disease to decide which strain will affect the most people each year. Then, that year's flu shot is made to match that strain. Some years, the scientists are very accurate. Other years a different strain takes over, and the flu shot is less effective.

No matter what, the shot takes a week or two to become effective. It's possible to catch the flu before the shot "kicks in." That's probably why some people think the shot can cause the flu.

Other Ways to Prevent the Flu

Other types of flu vaccine may not be good choices if you're pregnant. Flu vaccine is available in a nasal spray, but it's a different formula. The nasal mist vaccine contains weakened flu virus, not killed virus. It's not FDA approved for pregnant women.

Keeping the flu away from your family members will help keep you healthy. Consider getting flu shots for everyone in the household so they'll be less likely to bring the flu virus home.

Wash your hands often and make sure that family members do the same. Avoid close contact with anyone who's sick. Staying a few feet away can help protect you from catching the virus. Wash your hands after touching anything a person with the flu has touched.

Flu Shot and Pregnancy