The two vaccines most pregnant women should get are the flu shot and the tetanus, diphtheria, and acellular pertussis vaccine or Tdap.
The flu shot is, of course, given seasonally. It’s recommended because women’s immune systems are affected by pregnancy, and they’re more likely to get seriously sick from influenza.
Tdap is a bit different — it protects newborns against pertussis or whooping cough. It’s a very contagious disease especially for infants and it can make them seriously ill. According to the Centers for Disease Control and Prevention, half of babies who get pertussis end up in the hospital, and some die.
Read more including a table on vaccines to avoid while pregnant and those recommended for new moms in special situations: Pregnancy Vaccine Protects Newborns From Whooping Cough : Shots – Health News : NPR