Hi pumpkin (love the name)
I don't actually teach attack. (BodyStep, Balance and Pump only). However have taught and did teach freestyle hinrg classes throughout two pregnancies. So to answer your question yes it is safe to do BodyAttack throughout your pregnancy as long as your pregnancy progresses normally and that you feel comfortable doing so.
Your plan to do low impact is great. Lisa Osborne was pregnant not so long ago and I'm sure must have given pregnancy options on one of the BA releases, she did in step approximately 18months ago???? Check out an older BA DVD, or chorry notes you'll probably find something there that will help.
Congratulations and good luck with the pregnancy.
Cheers
Always Be the Best You Can, Never Ever, Ever Give Up! Dare to be Different!