I wouldn't advise a bike unless it is stationary, balance is a little off haha. Have you been exercising throughout the pregnancy? I would talk to your doctor first, and see what they suggest for exercise. Things like yoga, walking, swimming, etc all are recommended typically. Low impact seems to be the most common.
I'm not so sure squats would be good. Your hips and pelvic floor are already under a lot of pressure and loosened. I agree with the above swimming and yoga are great. Swimming works the whole body and takes the pressure of pregnancy off your body.
It all depends what kind of exercise you have been doing. The obvious and really great ones for pregnancy is yoga and swimming. I continued to do my weight training which including squats and boxing but I had been doing that before I was pregnant and I just monitored my weight and how my body reacted. Talk to your midwife/doc for recommendations for you