The Vaccines You Need During Pregnancy

Catherine Roberts

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Consumer Reports has no financial relationship with advertisers on this site.

Scientists have long known that the flu can be dangerous for pregnant women. Now, a study published today in the journal Birth Defects Research shows that it may harm a developing fetus, too.

Women who were hospitalized for the flu during the 2009 pandemic were more likely to deliver preterm, and their infants were more likely to have low birth weights and be in poorer overall health, compared with women who didn’t get the flu, according to the new study.

But other research suggests there’s an easy way of reducing the risk to both mother and baby. Getting the flu shot can cut a pregnant woman’s chances of being hospitalized because of the flu by about 40 percent, according to a study published recently in the journal Clinical Infectious Diseases.

And earlier research suggests that Tdap, the adult vaccine against tetanus, diphtheria, and pertussis (whooping cough), can reduce the likelihood that an infant will catch whooping cough during the first two months of life by 78 percent.

Both the flu shot and the Tdap are recommended during pregnancy. But only about half of pregnant women received these vaccines during the very severe 2017 to 2018 flu season, according to a survey from the Centers for Disease Control and Prevention.

That’s a problem, experts say. “Even during a relatively mild season, there end up being thousands of women who are hospitalized with pregnancy complications,” says Mark Thompson, Ph.D., an epidemiologist with the CDC’s influenza division. “When these hospitalizations occur, it puts the mother at risk, it puts the baby at risk.”  

And a case of pertussis can be fatal to infants: About half of babies younger than a year who come down with the illness are hospitalized, and 1 in 100 of those who are hospitalized die.

Women are advised to avoid many medications during pregnancy, and some may be fearful of having shots during this time, too. But scientists say these two vaccines are both important and safe. Here’s what you need to know.

The Flu Shot During Pregnancy

A flu shot is recommended during each pregnancy, and it’s fine to get at any point. If you’re pregnant before flu season begins, try to be vaccinated by the end of October so that you’re protected before the season gains momentum. (If you haven’t gotten vaccinated yet this season, it’s still not too late, and you should get the shot as soon as possible.)

Having a flu shot during pregnancy will protect your baby from the flu during the first six months of life, before he or she is old enough to be vaccinated.

But it’s also critical for expectant moms. Pregnant women have a much greater chance than their nonpregnant peers of developing a serious complication, such as high fever, pneumonia, or sepsis—or even dying—if they come down with the flu.

The main reason is that the immune system can’t fight infections as easily during pregnancy because it’s busy protecting the fetus, as well as mom, says Laura Riley, M.D., an obstetrician and the gynecologist-in-chief at NewYork-Presbyterian/Weill Cornell Medical Center. 

And not only are you more likely to get sick, but women with severe viral infections—whether flu or another type of virus—who have prolonged fever are at increased risk for preterm birth, Riley says.

If you’re concerned that the shot might harm you or your baby, numerous studies over the years have demonstrated that it’s safe—and that it can’t give either of you the flu (though it might cause temporary side effects, such as arm pain or a low fever).

But note: Get the flu shot, not the nasal spray flu vaccine, which is made with a live attenuated (or weakened) flu virus. Vaccines made with live attenuated viruses aren’t recommended for pregnant women.

About the Whooping Cough Vaccine

Pregnant women should receive a dose of Tdap during every pregnancy, sometime between the 27th and 36th week, according to the CDC.

Pertussis, or whooping cough, a bacterial illness that can cause intense coughing fits, is usually no more severe during pregnancy than at other times of adult life, according to Jeanne Sheffield, M.D., director of the division of maternal-fetal medicine and a professor in the Johns Hopkins Medicine department of gynecology and obstetrics.

But it can be highly dangerous for infants, and babies don’t start receiving the DTaP series—the childhood vaccine against diphtheria, tetanus, and pertussis—until they’re 2 months old.

“Infected infants may develop pneumonia, convulsions, encephalopathy, and death,” Sheffield says.

Tdap is safe for pregnant mothers and their babies, according to a good deal of research.

Are There Other Vaccines You Should Get?

Tdap and flu are the only vaccines recommended for all pregnant women, but some people may need additional shots—so check with your doctor.

Women who’ve been exposed to hepatitis B, for instance, should receive a vaccination against it.

If you’re planning to travel internationally while you’re pregnant, ask whether you should receive any vaccines to protect from diseases that are common where you’re going.

And if you get pregnant and are missing any vaccinations you should have received in childhood, such as a dose of MMR, the vaccine against measles, mumps, and rubella, ask your doctor whether you need to get caught up.

These can be administered right after you give birth—that will help keep you from getting sick, and if you breastfeed, you’ll pass some antibodies to those illnesses on to your baby via your breast milk.

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