can exercise cause a m/c?

I was just wondering if exercise cause a m/c. My dr. has assured me that it cannot, but I had a m/c around 12 weeks on Sept 4 & then a chemical preg. on 12/4. Both times I was using my elliptical machine. I think I am just being paranoid, but now I am wondering if this is what cause both my m/c I am in very good health & try to live an active life. I was just wondering if anyone's dr. told them to take it easy & not exercise.

[AnnieBrooke]

Exercise does not cause a miscarriage.  As Andi says, "You cannot shake a good egg loose."

[hawesmead5]

When I was first pregnant in the first 8 weeks before I knew I was pregnant I was exercising more thaan I ever have. I was competing in fell races and still winning some of these. I was running for about 2 hours each night recording some very fast times. I am now 20 weeks pregnant and I still run 3 times a week on my treadmill, obviously nothing like I was doing before and at a very slow jogging pace. Before continuing running I did a lot of research into how this can effect you and your baby. No exercise can cause you to have a m/c and exercising throughout your pregnancy is actually benefical to you and your baby as long as your heart rate doesn't go too high, you are well hydrated and you warm up and cool down properly.

[jayhawk822]

It's all in what you are used to.  I excercise off and on-when I tried to after I got pg, I was incredibly out of breath and heart raced.  Obv I slowed way way down and stopped.  If you were that miserable, I am sure you would not have continued.  That is the only time I heard it can cause any problems....