Tori Spelling is pregnant! The reality star has just confirmed via Twitter that she and husband Dean McDermott are expecting their third child this fall. And this time, they won't be finding out the sex. Tori, brace yourself for total strangers to size up your bump and tell you what it's gonna be - it's happened to me every day this month, and I'm not even famous.

So how do pregnant celebs like Spelling (and Victoria Beckham, Natalie Portman, Kate Hudson, Selma it something in the L.A. water?) stay in shape for the nine months their body's taken over by a little person who expands their middle and throws them off-balance? Options abound.

Swimming. "When I am in my womb-like environment, I am hoping the baby is feeling peaceful," Natalie Portman told Us Magazine. Try "water-walking" or jogging - the water creates a natural resistance. Sneak in a little strength training by using flotation weights as dumbbells.

Walking. Challenge yourself by setting out with a pedometer and a stopwatch, aiming for one mile. As you get stronger and faster, try to walk one mile in under 20 minutes - gradually shaving your time to 15.

Yoga. With the right modifications, yoga will keep your new body flexible and balanced, build strength in your arms and legs, and prepare you physically and mentally for "D-Day."

Cardio. No need to shy away from the gym - just prepare for those random gender predictions in the locker room. Hit the treadmill for a fast walk or slow jog, or try the recumbent bike while you can still squeeze in behind the handle.

Squats and lunges. They'll fight leg swelling, promote circulation, and strengthen your legs for delivery. Best bet is to lower against a wall or holding onto a chair, to work your quads and glutes without aggravating your back or throwing off your balance.

Blogger Melissa Pheterson

Melissa Pheterson is a health and fitness writer and trend-spotter. Follow her on and on Twitter @preggersaspie.