Previous advice I have read said it's ok to do cardio such as spinning (low impact after all) whilst pregnant as long as you keep your heart rate reasonable. I keep mine to 140 BPM max (have a garmin) and my midwife was horrified yesterday that I am still doing it 1-2 times per week.
Any views / experience on this? I was relatively fit before pregnancy and just wanted to maintain a little really. Am 25 wks today!