A pregnant woman's Tdap vaccine will help protect her newborn against pertussis (whooping cough) until he's old enough to get his own shots.
pregnant woman getting vaccine in doctors office
Credit: Ariel Skelley/Getty Images

Getting vaccinations while pregnant sounds scary, but the shots can be your baby's best chance at avoiding scary illnesses. In fact, a 2017 study by the Centers for Disease Control and Prevention (CDC) published in the journal Clinical Infectious Diseases proves that getting the Tdap vaccine (tetanus, diphtheria and pertussis) in the third trimester drastically reduced babies' risk of developing whooping cough, also called pertussis. The illness can be fatal in newborns. 

The study looked at three years' worth of data from six states around the U.S. "We found that vaccinating pregnant women at 27 to 36 weeks' gestation was 78 percent effective at preventing pertussis in babies less than eight weeks of age—when they're too young even to have received their first pertussis vaccine," study author Paul Cieslak, M.D., medical director of Communicable Diseases and Immunizations at the Oregon Health Authority, tells Parents.com. The vaccine was also shown to be 90 percent effective at preventing serious cases of the disease that required hospitalization.

Tdap Recommendations for Pregnant Women

Whooping cough causes uncontrollable coughing that makes it hard to breathe, and it’s extremely contagious. Before the vaccine for children was developed, there were more than 200,000 cases per year in America.; that number dropped drastically to fewer than 10,000 after the vaccine came out. "The vaccine has significantly decreased the number of cases," summarizes David F. Colombo, M.D., division chief of maternal fetal medicine at Spectrum Health in Grand Rapids, Michigan.

In 2012, the CDC recommended that women get the Tdap vaccine in every pregnancy—preferably between 27 and 36 weeks. The decision was supported by the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics. 

"If the mother is exposed to a disease, she will make antibodies to it. She'll give those antibodies to the child in the uterus and in the initial breast milk," says Dr. Colombo. "Giving the vaccine in the third trimester ensures that the mother will have higher antibody levels to pertussis so that she can give them to her child." 

In the Clinical Infectious Diseases study, the mothers of babies who came down with the sickness were less likely to have been vaccinated. "We have no doubt that infants, especially those less than two months of age, are at very high risk for pertussis—high percentages of whom do require hospitalization—and most of the deaths from pertussis are suffered by these young babies," says Dr. Cieslak. 

Is The Whooping Cough Vaccine Safe While Pregnant?

Despite what anti-vaccine websites say, the Clinical Infectious Diseases study and other research (including two studies from the UK and two from California) support Tdap’s safety and efficiency. "I get very concerned when people state that they refuse the vaccine or encourage other people around them to refuse the vaccine as well," Dr. Colombo says. "This leaves a group of unprotected people more susceptible to getting sick."

And those worried about potential pregnancy complications from the vaccine can rest easy. "It's worthwhile to ask whether any medicine is safe to give during pregnancy, so we're always on the lookout for potential side effects," Dr. Cieslak says. "The data are convincing that Tdap is safe during pregnancy. Studies involving tens of thousands of women haven't found any risk to the baby."

Most side effects to the Tdap vaccine are mild, and they include headache, body aches, and fatigue. It’s also common to experience swelling, redness, and/or pain at the injection site.