Jenni,
It would really depend on how far along you are. When I was pregnant with my b/g twins, I didn't do much in the impact department during my first trimester due to fatigue and sickness. (I don't call it morning sickness, it knows no time limits!) The usual advice is to take it easy as to intensity because you don't want you temp to get too high. BUT, if you are more interested in the arm drills for some variety, I'd say to give it a try and just listen to your body. As you get further along, you will definitely be doing that alot. I gained about 50 pounds during my twin pregnancy, and that's quite an adjustment for your body to make. (Especially since the majority is jutting out over your feet!) As long as you feel ok and ease yourself into it, I think it would be good for you.
Take care & good luck!
Tricia
aka, Isabella, Philip Anthony and Marissa's Mom!
Tricia