Found this online, hope it helps
Recently, the American College of Obstetricians and Gynecologists set out guidelines for exercise during pregnancy. The following is a synopsis of those guidelines:
1. Regular exercise (at least three times per week) is preferable to intermittent activity.
2. Vigorous exercise should not be performed when mom-to-be is ill, or during hot, humid weather.
3. Jerky, bouncy motions should be avoided. Exercise on a wooden floor or a tightly carpeted surface.
4. Because of the relaxation of connective tissue, pregnant women should avoid extreme stretching exercises.
5. Vigorous exercise should be preceded by a five-minute warm-up, such as slow walking.
6. Strenuous exercise should be followed by a period of gradually declining activity that includes gentle stretching.
7. Heart rate should be measured at times of peak activity and probably should not exceed a maximum of 150 beats per minute. (There are reports of pregnant, high-level competitive athletes who approached and even exceeded the recommended maximum heart rate without any apparent harmful effects on the fetus, but consult with your care provider if you have concerns.)
8. Care should be taken to rise gradually from the floor to avoid an episode of dizziness (from low blood pressure) related to changes in position. Some form of activity involving the legs should be continued for a brief period.
9. Liquids should be taken liberally before and after exercise to prevent dehydration. If necessary, activity should be interrupted to replenish fluids.
10. Women who have led sedentary lifestyles should begin with physical activity of very low intensity and advance activity levels very gradually.
11. Activity should be stopped and a care provider notified if any unusual symptoms appear.
