Safety of tetanus, diphtheria, and acellular pertussis vaccination among pregnant active duty U.S. military women

Abstract

Background: The tetanus, diphtheria, and acellular pertussis (Tdap) vaccine was approved for U.S. adults in 2005 and recommended for administration in every pregnancy in 2012, with optimal timing between 27 and 36 weeks' gestation. In the military, however, a current Tdap vaccination status is compulsory for service, and active duty women may be inadvertently exposed in early pregnancy. Safety data in this population are limited.

Objectives: To assess safety of inadvertent (0-13 weeks' gestation) and recommended (27-36 weeks' gestation) exposure to the Tdap vaccine in pregnancy.

Methods: Pregnancies and live births from Department of Defense Birth and Infant Health Research program data were linked with military personnel immunization records to determine pregnancy Tdap vaccine exposure among active duty women, 2006-2014. Multivariable Cox and generalized linear regression models estimated associations between Tdap vaccine exposure and adverse pregnancy or infant outcomes.

Results: Of 145,883 pregnancies, 1272 were exposed to the Tdap vaccine in the first trimester and 9438 between 27 and 36 weeks' gestation. Neither inadvertent nor recommended vaccine exposure were associated with spontaneous abortion, preeclampsia, or preterm labor. Among 117,724 live born infants, 984 were exposed to the Tdap vaccine in the first trimester and 9352 between 27 and 36 weeks' gestation. First trimester exposure was not associated with birth defects, growth problems in utero, growth problems in infancy, preterm birth, or low birth weight. Tdap vaccine exposure between 27 and 36 weeks' gestation was not associated with any adverse infant outcome.

Conclusions: Among a population of active duty women in the U.S. military who received the Tdap vaccine during pregnancy, we detected no increased risks for adverse maternal, fetal, or infant outcomes. Our findings corroborate existing literature on the safety of exposure to the Tdap vaccine in pregnancy.

Keywords: Maternal immunization; Military; Pregnancy; Tdap; Vaccine safety.