HealthDay News — Getting a tetanus-diphtheria-pertussis (Tdap) vaccine during pregnancy appears safe for the fetus, results of a study published in Journal of the American Medical Association indicate.

To assess the safety of the Tdap vaccine in pregnancy, Elyse Kharbanda, MD, MPH, of the HealthPartners Institute for Education and Research in Minneapolis, and colleagues gathered data on 123,494 women with pregnancies ending in a live birth between 2010 and 2012. Of those women, about one of every five received the Tdap vaccine during pregnancy.

Preterm delivery rates did not vary dramatically between the vaccinated and the unvaccinated, nor did rates of babies born with low birth weight. Among all pregnancies, 8.4% of patients who received Tdap during pregnancy and 8.3% who were not vaccinated had a baby with low birth weight.

The rate of preterm delivery among women receiving Tdap during pregnancy at 36 weeks or earlier was 6.3%, whereas the rate for unvaccinated women was 7.8%. The vaccine also did not significantly increase the women’s risk of preeclampsia or any other diseases linked to high blood pressure during pregnancy, added the investigators.

Patients who received the Tdap vaccine had a slightly increased risk of chorioamnionitis: 6.1% in vaccinated patients compared with 5.5% in unvaccinated women. However, the inflammation did not appear to cause an increased number of premature deliveries, which is the major threat posed by chorioamnionitis during pregnancy.

“Receipt of Tdap during pregnancy was not associated with increased risk of hypertensive disorders of pregnancy or preterm or SGA birth, although a small but statistically significant increased risk of chorioamnionitis diagnosis was observed,” concluded the researchers.


  1. Kharbanda E et al. JAMA. 2014; doi: 10.1001/jama.2014.14825