What are the risks of pertussis (whooping cough) vaccination during pregnancy?

Updated: May 02, 2019
  • Author: Joseph J Bocka, MD; Chief Editor: Russell W Steele, MD  more...
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A study found that the pertussis vaccine did not increase the risk of adverse birth outcomes in an observational study of 123,494 women who gave birth to a live singleton infant, including 26,229 who received the acellular pertussis vaccine (Tdap) during pregnancy. [38, 39]  Crude estimates for preterm delivery were 6.3% among vaccinated women and 7.8% among unvaccinated women (adjusted risk ratio [RR] 1.03). Estimates for small for gestational age birth were 8.4% in vaccinated women and 8.3% in unvaccinated woman (adjusted RR, 1.00). Women who received Tdap before 20 weeks were not at increased risk for hypertensive disorder of pregnancy (adjusted RR, 1.09). The study did find a small but statistically significant increased risk of chorioamnionitis with Tdap vaccination during pregnancy. Chorioamnionitis was diagnosed in 6.1% of vaccinated women and 5.5% of unvaccinated women, for an adjusted risk ratio of 1.19. [38, 39]

A case-control evaluation by Skoff et al on 240 pertussis cases in newborns under months old reported that the vaccine effectiveness estimate for Tdap administered during the third trimester of pregnancy was 77.7% (95% confidence interval [CI], 48.3%-90.4%) and vaccine effectiveness increased to 90.5% when looking at just the serious cases of pertussis that required hospitalization (95% CI, 65.2%-97.4%). [40]

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