Autism rates were slightly lower in infants born to women who had the Tdap shot.

A new study published in the journal Pediatrics has found that Tdap vaccinations for pregnant women do not increase the risk of autism spectrum disorder in their children.

The study assessed more than 80,000 children born between 2011 and 2014 at Kaiser Permanente Southern California hospitals.

Children of mothers who received the Tdap vaccine while pregnant were no more likely to develop autism than children of mothers who did not receive the vaccine while pregnant.

In fact, the prevalence of autism was slightly lower in children of Tdap-vaccinated mothers.

The autism rate for infants born to mothers who had the vaccine was 1.5 percent compared to 1.8 percent for women who did not have the vaccine.

This study adds to a large body of research that shows no link between vaccinations and autism.

“There is no relationship between autism and any vaccine,” Dr. Daniel Coury, a pediatrician at Nationwide Children’s Hospital, told Healthline.

Coury also stressed that parents should not agonize over the components of the vaccine.

“There’s also no relationship between autism and any component of any vaccine,” he said, “including the various other things that are put into vaccines as preservatives or stabilizers to ensure that they’re going to maintain their effectiveness.”

The Tdap vaccine provides protection against three potentially deadly diseases: tetanus, diphtheria, and acellular pertussis, also known as whooping cough.

From age 2 months to 6 years, most children receive a series of vaccinations against whooping cough, diphtheria, and tetanus. But it takes time for the protective effects to kick in.

Among the most dangerous for infants is whooping cough, a highly contagious respiratory infection that can make it hard to breath. Children often cough for so long all the air is forced from their lungs, resulting in the characteristic “whoop” when they try to catch their breaths.

Young infants, especially those under 6 months who are too young to fully vaccinate, are vulnerable to severe and fatal cases of whooping cough.

“The highest risk for severe morbidity as well as mortality is in young infants, particularly in the first couple of months of life,” Dr. Geeta Swamy, associate professor and vice chair for research in the department of obstetrics and gynecology at Duke University School of Medicine, told Healthline.

To protect newborns and young babies, the Centers for Disease Control and Prevention (CDC) encourage pregnant women to receive the Tdap vaccine in the third trimester of pregnancy.

Antibodies from the pregnant mother provides some protection to the infant in 91 percent of cases, according to the study authors.

The American College of Obstetricians and Gynecologists and Society for Maternal-Fetal Medicine have also endorsed this recommendation.

“The idea is that by vaccinating the mother with the Tdap vaccine while she’s pregnant, the antibodies that her body generates in response to the vaccine then cross the placenta and stick around in the baby after birth,” said Swamy.

Pregnant women are also encouraged to get the influenza or “flu” vaccine.

Swamy hopes that studies like this one can help reassure people who have concerns about the risks of potential vaccines.

“Obviously pregnant women and their families are very concerned about what they might be doing during pregnancy — what medications they take, what they eat, all these things that they’re being very careful about to try to ensure the best outcome for themselves and their child-to-be,” she said.

Swamy said this kind of research can help patients feel reassured that vaccines are safe for them and their infants.

Misconceptions about the risks of vaccines have led some parents to avoid vaccinating their children. As vaccination rates have fallen, some preventable diseases have made a comeback.

“One of the problems is that vaccinations and immunizations have been so successful that many people today have never seen some of these diseases, and as a result, they don’t appreciate how horrible some of them are,” Coury said.

The CDC reported there have been 107 cases of measles in 21 states, just this year.

“Sometimes there’s a misconception that these are mild diseases and not harmful,” he said. “But that’s really not true, and we’ve seen that in recent years with measles outbreaks and whooping cough outbreaks in areas of the country where vaccination rates have dropped.”

In 2012, for example, more than 48,000 cases of whooping cough were reported in the United States — making it the worst year for whooping cough since 1955.

The 20 people who died from that outbreak included 15 infants under 3 months old.

“It’s tragic that we’ve had to see children affected by these diseases,” Coury said, “but these are reminders that if we maintain high vaccination rates, we can keep a very healthy population.”

To learn more about the many benefits and limited risks of vaccination, he encourages people to seek out credible sources of information, such as or

Coury and Swamy also encourage people to speak with their pediatricians, obstetricians, or primary care providers to learn which vaccines are recommended at different stages of life.