My opinion : The first trimester is very critical... the best is not to pick up and weight at all.
40smama is right... ask your doctor... he/she can give you better answer..
I am 8 weeks pregnant and I am afraid to lift and weight... I used to go to the gym everyday for 2 hours... now I have to postpone all that until my first trimester pass.. then i can go back to the gym and do light exercise.
good luck to you.. and take care
Ask your doctor - I can tell you what I've read or what my doctor told me - to continue an exercise regiment that you've been doing - he encourage his patients not to begin a new rigorous program that they aren't used to doing.
If you're used to lifting weights, I would think moderation is the key - I don't see why you can't continue w/your program. But to be on the safe side, clear all of this w/your ob.