Pregnancy outcomes after antepartum tetanus, diphtheria, and acellular pertussis vaccination

To evaluate pregnancy outcomes of women who received tetanus, diphtheria, and acellular pertussis (Tdap) vaccination at or after 32 weeks of gestation. Outcomes from consecutive pregnancies during which the mother received Tdap were also analyzed.

In a retrospective cohort study at a single institution, we compared pregnancy outcomes between those who accepted or declined Tdap at 32 weeks of gestation. Additionally, women who received Tdap vaccination in this and a prior pregnancy in the past 5 years were compared with multiparous women who only received Tdap in this pregnancy.

Since 2013, 7,378 women who were offered the Tdap vaccine antenatally delivered at our institution: 7,152 accepted (97%). There was no difference in stillbirths, major malformations, chorioamnionitis, 5-minute Apgar score, or cord blood pH. Neonatal complications including ventilation requirement, sepsis, intraventricular hemorrhage, and neonatal death were also similar. However, preterm birth rates at 36 weeks of gestation or less (6% compared with 12%, P<.001), incidence of small for gestational age (10% compared with 15%, P=.03), and length of neonatal hospitalization (3.9 compared with 4.7 days, P<.001) were all significantly increased in the unvaccinated cohort. No difference in neonatal outcomes was noted between women who were administered at least two Tdap vaccines in the past 5 years (n=1,229) and those who received only a single dose (n=4,159).

No adverse pregnancy outcomes were identified in association with antepartum Tdap vaccination. This remained true in women receiving more than one Tdap vaccine in a 5-year timeframe. This may be the result of a type II error.

II.