Tdap and fetal anomalies: no increased risk seen, even with first-trimester vaccination

  • Kerr SM & al.
  • Birth Defects Res
  • 05/01/2020

  • Liz Scherer
  • Clinical Essentials
L'accesso ai contenuti di questo sito è riservato agli operatori del settore sanitario italiano L'accesso ai contenuti di questo sito è riservato agli operatori del settore sanitario italiano

Takeaway

  • Tetanus toxoid-reduced diphtheria toxoid-acellular pertussis (Tdap) vaccination in pregnancy is not associated with increased risk for fetal anomalies, even among women who are inadvertently exposed to vaccination in early pregnancy.

Why this matters

  • European Centers for Disease Control country-by-country recommendations call for administering the Tdap vaccine to pregnant women between 20 and 36 weeks of gestation.

Key results

  • 2460 Tdap vaccine-exposed participants:
    • 103 pre-last-menstrual period or postdelivery, 2357 any time during pregnancy: 103 in first trimester, 2256 in second or third trimesters, 2 in both periods.
  • Malformations risk, first-trimester exposures: aOR, 1.0 (95% CI, 0.7-1.5).
  • Propensity score-adjusted (defects, ≥5 cases) risks ranged from:
    • aOR, 0.5 (95% CI, 0.4-0.7) for undescended testicles to
    • aOR, 1.3 (95% CI, 0.5-3.0) for conotruncal/major arch.
  • Sensitivity scoring for above differed by ≤0.2.
  • Second- or third-trimester exposure, propensity score-adjusted risk
  • aOR, 0.5 (95% CI, 0.4-0.7) for undescended testicles to
  • aOR, 0.9 (95% CI, 0.7-1.12) for clubfoot.
  • Risk estimates for isolated cases were similar.
  • Study design

    • Retrospective, longitudinal analysis of birth defects data assessing link between late/early Tdap exposure and specific birth defects (including those developing in late pregnancy).
    • Funding: US National Vaccine Program Office; others.

    Limitations

    • Self-report exposures, genetic conditions biases.
    • Retrospective.