The Advisory Committee on Immunization Practices (ACIP) recommends the tetanus, diphtheria, and acellular pertussis (Tdap) vaccine for pregnant women during each pregnancy, regardless of prior immunization status. However, safety data on repeated Tdap vaccination in pregnancy is lacking.
To determine whether receipt of Tdap vaccine during pregnancy administered in close intervals from prior tetanus-containing vaccinations is associated with acute adverse events in mothers and adverse birth outcomes in neonates.
There were no statistically significant differences in rates of medically attended acute adverse events or adverse birth outcomes related to timing since prior tetanus-containing vaccination.*
Among women who received Tdap vaccination during pregnancy, there was no increased risk of acute adverse events or adverse birth outcomes for those who had been previously vaccinated less than 2 years before or 2 to 5 years before compared with those who had been vaccinated more than 5 years before.
These findings suggest that relatively recent receipt of a prior tetanus-containing vaccination does not increase risk after Tdap vaccination in pregnancy.*
[F]ew published studies have evaluated the safety of Tdap vaccine in pregnant women.
Most safety studies on administering repeated doses of tetanus-containing vaccines are limited to nonpregnant individuals.
We included women aged 14 through 49 years who received Tdap vaccine during pregnancy and had continuous insurance coverage from 6 months prior to pregnancy to 6 weeks postpartum…
We excluded women… with a multiple gestation pregnancy.
We also excluded pregnancies with non-live birth outcomes (stillborn, spontaneous abortion [miscarriage], therapeutic abortion, trophoblastic disease, and ectopic pregnancy)…
Our findings are similar to another retrospective cohort study evaluating women receiving Tdap in pregnancy who had a prior pregnancy with Tdap vaccine administered within 5 years compared with multiparous women with no prior Tdap vaccine in pregnancy. This study [referenced in comments below**] found no difference in gestational age at delivery, stillbirth, major malformations, neonatal care admissions, ventilation requirements, and neonatal death, whereas ours focused on preterm delivery, small for gestational age, and low birth weight.**