Tdap is a vaccine–containing tetanus and pertussis. A new immunization schedule recommends that a dose of the Tdap vaccine be given to all women during each pregnancy, whether or not she has received the vaccine before. This is a change!
This may seem a bit extreme, but the basis of the new recommendation is clear. There has been a HUGE pertussis epidemic with more than 40,000 cases reported last year, infants disproportionately affected. Of note, most pertussis deaths and hospitalizations occurred in babies under 3 months of age.
How does this work? It is thought that a Tdap in the last third of the pregnancy provides immunity to the mother with effective antibody response and placental transfer of pertussis antibodies to the fetus. In addition the “cocooning” strategy speculates the vaccine likely provides passive immunity for infants even after birth, until the first Tdap vaccine is given to the baby at a routine well child check.
Are there risks with giving this to the mother and fetus? None known. To date, there is no data suggesting increased fetal, maternal or pregnancy risks.