Prenatal tetanus, diphtheria, acellular pertussis (Tdap) vaccination does not increase the risk for autism spectrum disorder (ASD) development in offspring, according to a retrospective cohort study published in Pediatrics.

Currently, the Advisory Committee on Immunization Practices (ACIP) recommends pregnant women receive the Tdap vaccination to prevent pertussis infection. To investigate the association between Tdap vaccination and ASD risk, researchers from Kaiser Permanente evaluated 81,993 children born over a 4-year period (2011 to 2014) for an autism diagnosis. In the 2012 birth cohort, 26% of mothers received the prenatal Tdap vaccine, whereas 79% of mothers were vaccinated in the 2014 birth cohort. 

Results showed the incidence rate of ASD in children was 1.5% in the maternal Tdap vaccinated group (3.78 per 1000 person-years) compared with 1.8% in the maternal unvaccinated group (4.05 per 1000 person-years). These rates were comparable to that of autism incidence in the US at 1.7%. An analysis of the data showed that Tdap vaccination during pregnancy was not associated with increased ASD risk in children (HR 0.85, 95% CI, 0.77–0.95). These results were similar across study birth years and parity. 

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“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,” stated lead author Tracy A. Becerra-Culqui, PhD, a post-doctoral research fellow with Kaiser Permanente Southern California’s Department of Research & Evaluation. 

“The link between vaccination and development of autism has been refuted by many rigorous scientific investigations. Unfortunately, the misconceptions still generate concerns,” added the paper’s senior author, Hung Fu Tseng, PhD, of the Department of Research & Evaluation. “We hope that our findings reassure parents that Tdap vaccination during pregnancy was not associated with autism in children.”

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