Obviously you need to have this conversaton with your doctor, but with that being said, I was very active throughout both my pregnancies. The advice I was given was to just do what I was already trained to do, but to be careful of over-heating (and avoid saunas and hot tubs, etc). We didn't measure our heart rates in those days, but nowadays I think it means just keeping your heart rate in the moderate versus high intensity zone. Congrats on the baby! An active preganancy leads to an easier birthing experience!