Do not lift heavy weights. If can really strain your back. My doctor suggested to me that if I still wanted to lift to lift light weights while sitting on the exercise ball. Also not to do actual squatting with weight for the same reason. But to do squats against the wall with an exercise ball in the arch of your back for support. But there is still so much to do. All the machines like treadmill and elliptical etc. are okay as long as you feel comfortable. I just gave up bikes about a month ago because i was to huge was hitting my stomach. And also planks along many of the leg machines even sitting leg press and still okay and very safe.
Okay! Well you should be fine, especially if you're already used to it! I'd say just don't go as hard as you would if you weren't pregnant'
Oh gosh yes sorry I meant weeks
If you don't mind me asking, did you mean 4-5 weeks? Or why are you finding out so late?