A vaccine that’s strongly recommended for pregnant women does not influence the odds that their children will develop autism, according to a large new study.

Researchers looked at data on more than 81,000 children born between 2011 and 2014 to assess the impact of the Tdap vaccination — which protects against tetanus, diphtheria and pertussis, also known as whooping cough — given during pregnancy. They found no association between women who received the shot and the likelihood of autism in their children.

“Pregnant women can be reassured by this study that there is no indication of an increased risk of autism spectrum disorder in children after being exposed prenatally to the Tdap vaccine,” said Tracy Becerra-Culqui of Kaiser Permanente Southern California’s Department of Research & Evaluation who led the study which was published this week in the journal Pediatrics.

The Centers for Disease Control and Prevention urges women to get the Tdap immunization during the third trimester of each pregnancy. Receiving the vaccine during this later stage of pregnancy allows antibodies to be passed to the child before birth, helping to protect babies in the first months of life before they can be vaccinated themselves.

For the study, researchers reviewed medical records of children born at Kaiser Permanente hospitals in Southern California. Of mothers who received the Tdap vaccine during pregnancy, 1.5 percent of their kids were later diagnosed with autism.

Meanwhile, 1.8 percent of children whose moms were not immunized prenatally were ultimately diagnosed with the developmental disorder, the study found.

“The link between vaccination and development of autism has been refuted by many rigorous scientific investigations. Unfortunately, the misconceptions still generate concerns,” said Hung Fu Tseng of Kaiser Permanente who worked on the study.

“Given the increasing practice to vaccinate pregnant women with Tdap vaccine, it was important to address the concern of a link between maternal vaccination and subsequent development of autism spectrum disorder in children,” Tseng said.

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