I am 11.5 weeks with my first pregnancy. I have been doing step aerobics and a toning step class on and off for about three years. Before becoming pregnancy, I had been going on a regular basis of at least three times per week and walking on the weekends. My doctor says that it's perfectly OK for me to do step aerobics as long as I don't let my heartrate go above 120. What do you think? I am pretty good at the class and do not easily stumble on the step, as some people do. Sometimes the instructor has awkward moves. But when I feel that one of her combinations is awkward, I just do something basic instead. Are step aerobics OK during pregnancy and if so, for how long?