Pertussis Vaccine Appears Safe in Pregnancy for Mom, Baby

By Anne Harding

November 14, 2014

NEW YORK (Reuters Health) - Pregnant women who receive the pertussis vaccine are not at increased risk of adverse birth outcomes, according to new findings published in JAMA.

"Our findings in this observational study support current use of pertussis vaccine in pregnancy," first author Dr. Elyse Kharbanda of the HealthPartners Institute for Education and Research in Minneapolis told Reuters Health in a telephone interview.

In 2010, the California Department of Health began recommending that women receive the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) during pregnancy, due to an outbreak of pertussis that led to 10 neonatal deaths. The following year, the Advisory Committee on Immunization Practices recommended that all pregnant women receive Tdap vaccination at 20 weeks' gestation or later. And in 2012, ACIP recommended that women receive Tdap during every pregnancy, ideally between 27 and 36 weeks' gestation, even if they had been immunized previously.

To investigate the safety of Tdap vaccine in pregnancy, Dr. Kharbanda and her team looked at data from two California Vaccine Safety Datalink sites on 123,494 women who gave birth to a live singleton infant between January 1, 2010, and November 15, 2012. Twenty-one percent (26,229) had received the Tdap vaccine while pregnant.

As reported online November 11, the vaccine was not associated with an increased risk of hypertensive disorders of pregnancy or preterm or small for gestational age (SGA) birth. However, 6.1% of the women who received the Tdap vaccine were diagnosed with chorioamnionitis, vs 5.5% of the unvaccinated women, for an adjusted risk ratio of 1.19.

"Physicians will pick up on the small positive association with vaccination and chorioamnionitis," Dr. Kharbanda told Reuters Health. "We just want to provide reassurance that the actual magnitude of the increase was quite small, and in chart review data we found that many women diagnosed with chorioamnionitis didn't have the full clinical picture of chorioamnionitis, so we would be very cautious about overinterpreting the results. We don't feel it should change immunization practices."


JAMA 2014.


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