what a tdap?

It's recommended everyone that's gonna be in immediate contact with the baby should be protected and it's important for you to get it to immunize the baby :)

Tdap is a combination vaccine that protects against three potentially life-threatening bacterial diseases: tetanus, diphtheria, and pertussis (whooping cough). Td is a booster vaccine for tetanus and diphtheria.

done during the 3rd trimester of every pregnancy

Whooping cough shot. Bassicly to (try) and prevent you or baby from getting whooping couch. Same concept as flu shot