Combined tetanus, diphtheria, and acellular pertussis (Tdap) vaccinations are safe during pregnancy, according to a new study. The CDC recommends Tdap vaccinations during each pregnancy, preferably during the third trimester when antibodies can be passed to the fetus, providing protection against pertussis during the first months of life. In 2014, Brazil began a prenatal Tdap vaccination program, which overlapped with the Zika outbreak. The subsequent increase in cases of infant microcephaly raised concerns that Tdap may be contributing to birth defects. Authors of this new study examined associations between maternal Tdap vaccinations and structural birth defects, including microcephaly in offspring. Researchers reviewed vaccination records of nearly 325,000 singleton births from six states from 2007 to 2013. About 13% of babies were exposed to Tdap. These infants were no more likely to develop structural birth defects, including microcephaly, than offspring of unvaccinated mothers. The findings were the same regardless of when the mother was vaccinated during pregnancy (JAMA 2016;316;1823-1825. DOI:10.1001/jama.2016.14432).