I was advised the same as Natty (although I am definitely NOT a competitive runner :P ) but I was cycling a lot and doing triathlons when I got pregnant.

The only additional advice I had was with cycling as your centre of gravity shifts when you get a bigger belly you can become unsteady on the bike. You can adjust your posture on the bike but as the belly gets bigger your knees tend to hit it and it puts more strain on your lower back as you leab forward. So you do need to watch those things even on a stationary bike.

With pump I was told not to do exercises where you lift weights above your head eg. int he shoulder track with shouler presses. I can't remember why though.