HealthDay News – Being immunized with the tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine during pregnancy is safe, according to a report published in JAMA.

“This preliminary assessment did not find an increased risk of adverse events among women who received Tdap vaccine during pregnancy or their infants,” wrote Flor M. Munoz, MD and researchers.

Between 30 and 32 weeks of gestation, 48 randomized pregnant patients aged 18 to 45 years received either Tdap (33 patients) or a placebo (15 patients), with crossover immunization postpartum. No Tdap-associated serious adverse events in patients or infants were observed. 

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After Tdap immunization, injection site reactions were reported in 26 pregnant and 12 postpartum patients (P>0.99). Of the pregnant patients, 12 reported systemic symptoms compared to 11 postpartum patients (P<0.001). Both infant groups showed similar growth and development. No pertussis occurred.

In patients who had received Tdap during pregnancy, significantly higher concentration of pertussis antibodies were measured at delivery, compared to patients receiving postpartum vaccinations (P<0.001).

Similar results were seen in their infants at birth (P<0.001) and aged 2 months (P<0.001). Antibody responses between the two groups of infants did not differ following the fourth dose of the Tdap vaccine.

“Further research is needed to provide definitive evidence of the safety and efficacy of Tdap immunization during pregnancy,” wrote the authors.


  1. Munoz F et al. JAMA. 2014. 311 (17).