Most American adults have some knowledge of what a healthy pregnancy entails. 

Most know that getting vaccinated for COVID-19 is safe during pregnancy, that flu shots protect pregnant people and their babies, and that untreated high blood pressure increases the likelihood that a pregnant person suffers a stroke, according to research conducted by the University of Pennsylvania. 

But only about 1 in 4 know that pregnant women should receive the Tdap vaccine, which provides protection against tetanus, diphtheria and pertussis. That finding is indicative of the significant knowledge gaps that Americans have about maternal health, researchers said. 

The Tdap booster is recommended for pregnant women because of the protection it provides infants from pertussis, also known as whooping cough. The respiratory infection is dangerous to babies because it can cause violent, uncontrollable shaking, brain disease and life-threatening pauses in breathing, according to the U.S. Centers for Disease Control and Prevention. Many babies with pertussis don’t cough at all, but turn blue and stop breathing. 

About 1,000 babies are hospitalized in the United States by pertussis each year, according to the Centers for Disease Control and Prevention. Pertussis kills about 5 to 15 infants annually, mostly among babies that are 2 months or younger. 

When women get vaccinated during pregnancy, they reduce the risk of their babies developing whooping cough before they turn 2 months old by 78%, the CDC says. That’s because the antibodies created by the vaccine are passed to the baby in the womb. They offer protection to the baby during its first two months of life, when it is too young to receive its own vaccine. 

The CDC recommends women get the Tdap booster between the 27th and 36th weeks of pregnancy, because that timeline provides optimal protection for their babies. It takes about two weeks to gain full protection from the vaccine. Getting vaccinated after giving birth does not provide any immunity to the baby. 

The CDC also recommends that pregnant people receive a Tdap booster with every pregnancy, even if it’s within a year of a previous pregnancy.

At 2 months, the CDC recommends babies begin receiving DTaP shots, which protect against diphtheria, tetanus and pertussis. They should receive additional doses at 4 months, 6 months, 15-18 months and 4-6 years. A Tdap booster should be given at age 11 or 12. 

Initial whooping cough symptoms include a runny nose, red and watery eyes, a sore throat and a slightly elevated temperature. Intense coughing bouts may occur about a week later. Among babies, the cough may not be noticeable, but they may have brief periods where they stop breathing.

Diphtheria is a bacteria that can build up in the throat, causing breathing difficulties, heart rhythm issues and death. Tetanus is a bacteria that causes causes the neck and jaw muscles to lock up, making it difficult to swallow.