BACKGROUND AND PURPOSE: 

• Becerra-Culqui et al. (Pediatrics, 2018) examined the association between prenatal tetanus, diphtheria, acellular pertussis (Tdap) vaccination and autism spectrum disorder (ASD)

METHODS: 

• Retrospective cohort study  
  • Mother-child pairs, members in an integrated healthcare system (15 hospitals/approximately 4.4 members) 
  • Restricted to live singleton infants 22 to 45 weeks’ gestation 
  • Mothers had to be members from start of pregnancy | Infants had to be members for at least 90 days after 1st birthday  
  • Maternal Tdap vaccination from pregnancy start to delivery date obtained from electronic medical records 
• Children were managed from birth to first ASD diagnosis, end of membership, or end of follow-up (3 years) 
• Adjustments were made for  
  • Child’s birth year | Gestational age at birth (<37 or ≥37 wk) | Maternal age, race and/or ethnicity, and education | Medicaid insurance | Medical center of delivery | Parity | Start of prenatal care | Flu vaccine during pregnancy  
• Primary outcome was diagnosis of autism spectrum disorder (ASD) 
  • 12-month minimum for ASD diagnosis based on Autism Diagnostic Observation Schedule (Gold Standard diagnostic instrument)

RESULTS: 

• 81,993 children included in the study 
• Prenatal Tdap vaccination 
  • 26% for the 2012 birth cohort to 79% for the 2014 birth cohort 
  • Mean age of vaccination: 28 weeks to 29 weeks, respectively  
• 1341 children were diagnosed with ASD 
• The ASD incidence rate was 
  • 3.78 per 1000 person years in the Tdap exposed group 
  • 4.05 per 1000 person years in the unexposed group  
• Adjusted HR 0.85; 95% CI 0.77-0.95 demonstrated no association with increased risk for ASD

CONCLUSION: 

• Prenatal Tdap vaccination is not associated with increased risk of ASD 
• Minimal change in results with respect to parity or year of birth  
• The authors state  

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.

Learn More – Primary Sources: 

Prenatal Tetanus, Diphtheria, Acellular Pertussis Vaccination and Autism Spectrum Disorder

Related ObG Topics:

Vaccination in Pregnancy: CDC Recommendations and ACOG Update

Does Prenatal Tdap Vaccine Protect Infants From Pertussis? 

Are Tdap and Polio Vaccines Safe During Pregnancy?

Is there any Link between Maternal Vaccinations and Infant Hospitalizations or Death? 6 Month Infant Follow-up