I didn't with my first either whooping cough cases have increased over the years which is why they recommend it now in the 3rd trimester to help baby build immunity before he or she is born.
Because they've done more research that suggests a dose in the 3rd trimester can help protect baby until he/she can get the vaccine. I didn't do it with my first pregnancy either. It's always your choice.
I didn't get it my last pregnancy you really don't need it honestly it's totally up to you. I got it this time around though and I didn't feel good afterwords