November 01, 2016
1 min read

No link between Tdap vaccine during pregnancy, microcephaly

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Women who received the tetanus-diphtheria-acellular pertussis vaccine while pregnant were not more likely to have a child with microcephaly than those women who did not receive the vaccine, according to research published in the Journal of the American Medical Association.

“These results expand upon what is known about maternal [tetanus-diphtheria-acelluar pertussis (Tdap)] vaccination safety to include information about structural birth defects and microcephaly in offspring,” Malini DeSilva, MD, MPH, of HealthPartners Institute in Minneapolis, and colleagues wrote. “The findings support recommendations for routine Tdap administration during pregnancy.”

Researchers analyzed data from 324,463 live births from January 2007 through September 2013 to compare the prevalence of structural birth defects between offspring of women who received the Tdap vaccine and those who did not. Overall, there were 41,654 live births following maternal vaccination, with no increase in the rate of microcephaly (APR = 0.86; 95% CI; 0.60-1.24). These findings were consistent among women who received vaccination at the two discrete time periods researchers studied: fewer than 14 weeks gestation (3,321 births; adjusted prevalence ratio [APR] = 0.96; 95% CI, 0.36-2.58) or between 27 and 36 weeks gestation, the period recommended in 2012 by the U.S. Advisory Committee on Immunization Practices (20,568 births; APR = 1.01; 95% CI; 0.63-1.61).

Researchers wrote that their findings could be limited by the lack of information regarding birth defects that caused pregnancy loss or termination, wrongly identifying a woman’s immunization status, fragmental data on the Tdap vaccine and random variables such as the mother’s use of alcohol and diagnosed structural birth defects. – by Janel Miller

Disclosures: The researchers report no relevant financial disclosures.