In 2012, the US Advisory Committee on Immunization Practices recommended tetanus, diphtheria, and acellular pertussis (Tdap) vaccine be administered during every pregnancy, ideally between 27 and 36 weeks’ gestation.1 Previously, Tdap was recommended for unvaccinated pregnant women since 2010 in California and since 2011 across the United States.
Cases of microcephaly in Brazil increased substantially during 2015, likely associated with maternal Zika virus infections. However, these cases overlapped with the November 2014 initiation of Brazil’s maternal Tdap program.2 Previous small observational studies reported no increased risks for birth defects following maternal Tdap vaccination; none focused on microcephaly.3 This large study examined associations between maternal Tdap vaccination and structural birth defects, including microcephaly, in offspring.
DeSilva M, Vazquez-Benitez G, Nordin JD, Lipkind HS, Romitti PA, DeStefano F, Kharbanda EO. Tdap Vaccination During Pregnancy and Microcephaly and Other Structural Birth Defects in Offspring. JAMA. 2016;316(17):1823-1825. doi:10.1001/jama.2016.14432