If you can get yourself off the couch, then certainly you should go. My doctor just told me not to get my heart rate over 120 beats per minute, so your body temperature will not get too high as bub does not like being overheated, and I see everybody else got the same advise. Exercise is actually very good for the baby, when your heart rate goes up, bub's heart rate goes up too and his/her heart gets stronger. I excercised all the way through my first pregnancy and my daughter is strong like a bull :-)