Our bodies are meant to move and I'm sure there are marathoners who have gotten pregnant with all their training. Go for it, but if in doubt talk to your Dr.

Great advice karenwill50.  How much exercise did you do before?  I attended aerobic classes until 10 day before I delivered my 4th son.  I modified the work out and lowered the intensity.  Walking is always a safe bet.  I do agree with karenwill50 that you should be discussing this with your doctor.