Why Flu is Nothing to Sneeze at when You Are Pregnant

pregnancy flu

These days, this old ditty tends to evoke a smile more than anything else:

“I had a little bird,

Its name was Enza.

I opened the window,

And in-flu-enza.”

But nearly a century ago, the rope-skipping song about an oddly named bird symbolized the deadliest disease outbreak the U.S. has ever known: the 1918 “Spanish flu” pandemic, which killed an estimated 50 million people worldwide, including nearly 675,000 Americans.

The 1918 pandemic occurred about a quarter of a century before the US military developed the first flu vaccine to give to troops during World War II. In it, and in two pandemics that followed, pregnant women were more likely to die of the flu than people in the general population.

Today, though, many Americans, pregnant or not, have become cavalier about the flu. Relatively few of us know anyone who’s died of complications from influenza, which  is thought to kill thousands of Americans every year (for several reasons, including the fact that since states don’t have to report individual cases of seasonal flu, the Centers for Disease Control and Prevention (CDC) doesn’t know exactly how many die of the disease).

If you’re pregnant, though, it’s especially important to get a flu shot, according to the CDC and the American College of Obstetricians and Gynecologists (ACOG). Note that they specifically recommend getting a flu shot, not the nasal spray flu vaccine, which contains live, albeit weakened, flu virus, and is not approved for use in pregnancy.

Because of changes to the immune system during pregnancy, pregnant women are more likely to become seriously ill from the flu than people who aren’t pregnant.  That can lead to premature labor and delivery. Plus, a fever early in pregnancy can lead to birth defects. By getting a flu shot when you’re pregnant, you also help protect your baby after birth, research shows. That’s important, because babies younger than six months aren’t supposed to get vaccinated against the flu themselves.

The 2009 pandemic of the H1N1 flu virus, originally referred to as “swine flu,” confirmed that pregnant women are especially vulnerable to the flu, two CDC doctors wrote a year ago in The New England Journal of Medicine.

“Pregnant women with 2009 H1N1 influenza were at substantially higher risk for hospitalization than the general population, and they accounted for approximately 5% of deaths from H1N1 influenza that were reported to the [CDC], even though pregnant women make up only about 1% of the population,” Dr. Sonja Rasmussen and Dr. Denise Jamieson wrote. (But although pregnant women were more severely affected if they got the H1N1 flu, they did not appear to be more likely to become infected than people who weren’t pregnant, Rasmussen and Jamieson wrote.)

The H1N1 pandemic also provided information on the benefits of giving antiviral drugs such as Tamiflu to pregnant women who contracted the flu, according to the New England Journal article. Pregnant women had been excluded from studies of these medications before they came on the market. But among pregnant women hospitalized with the H1N1 flu, those who received one of the drugs within two days of onset of symptoms were far less likely to die than those who received the drugs later or not at all.

H1N1 spurred more pregnant women to get flu shots, especially in the first few years afterward. Since 2010, the proportion of pregnant women who received a flu shot has increased each year, reaching 52% during the 2013-2014 flu season, the CDC says. Of course, that means that roughly half of all pregnant women still aren’t getting a flu shot.

With virtually every drugstore, supermarket and workplace offering flu shots, it’s easier than ever to get immunized. And just because you’re pregnant doesn’t mean you need to bring a note from your doctor saying it’s okay for you to get a flu shot. If anyone gives you a problem about it, show him or her the CDC web page about flu misconceptions.

Rita Rubin
An ob-gyn's daughter and the mother of two teenage daughters, Rita Rubin has covered medicine ever since earning a BSJ from Northwestern. Based in Washington, D.C., Rita has written for WebMD, JAMA, POZ, and NBCNews.com and previously worked for USA TODAY. She has won numerous awards for her stories and authored What If I Have a C-Section? Rita earned an MA in writing from Johns Hopkins and spent a year as a fellow at the Harvard School of Public Health. You can follow her on Twitter @RitaRubin.

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