Is it safe to exercise while pregnant?

Yes. We generally encourage patients, with no contraindications, to exercise five days per week, 20-30 minutes a day. We usually avoid high impact-type of exercise. Walking, swimming, low-impact aerobics, exercise bike are all good types of exercise. Remember, calories in. And calories out (exercise), will help with proper weight gain in pregnancy. Ask your doctor.
Depends on situation. If you are in good basic health it is recommended. I've cared for infants whose mom taught jazersize classes up to the week of delivery & did fine. She was also back teaching a few weeks later.