Children were not at increased risk of autism after their mothers received tetanus, diphtheria, acellular pertussis (Tdap) vaccine during pregnancy, a new study found.
“Our results potentially indicate that the maternal Tdap vaccine affects immune trajectories protecting infants against infections that would otherwise lead to neurodevelopmental alterations,” the authors wrote.
The Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) recommends women receive Tdap vaccine during every pregnancy, preferably between the 27th and 36th week, to protect their infants from pertussis.
Studies have not found links between the vaccine and preterm delivery or low birth weight but had not looked at potential ties to autism. Researchers performed a retrospective cohort study of nearly 82,000 children who were delivered from 2011-’14 at Kaiser Permanente Southern California hospitals and reported the results today in “Prenatal tetanus, diphtheria, acellular pertussis vaccination and autism spectrum disorder” (Becerra-Culqui TA, et al. Pediatrics. Aug. 13, 2018, https://doi.org/10.1542/peds.2018-0120).
Following ACIP’s recommendation, vaccination rose from 26% in 2012 to 79% in 2014. Women were more likely to be vaccinated if they were Asian/Pacific Islander, educated, received prenatal flu vaccine and gave birth at term, according to the study.
About 1.6% of the children were diagnosed with autism. Among those whose mothers received prenatal Tdap, 3.78 were diagnosed with autism per 1,000 person-years compared to 4.05 per 1,000 person-years in children whose mothers were not vaccinated.
“We provide evidence supporting the ACIP’s recommendation to vaccinate pregnant women to protect vulnerable infants, who are at highest risk of hospitalization and death after pertussis infection,” authors wrote.