Just got mine a week and a half ago. I did a lot of research because I was worried about ANY vaccines during pregnancy (I didn't get a flu shot either). The pertussis vaccine makes sense. Your immunity to whooping cough is passed on to the baby since they normally wouldn't receive the pertussis vaccine until 2 months (or later). The problem with whooping cough is that in adults, it manifests as a common cold/slight cough. In babies, it's deadly. The positives of getting the vaccine far outweigh the negatives.
I got my shot 2 weeks ago. I was a little worried but I looked up the CDC report on the vaccine and found very low risk to baby. My arm was sore for a few days though.