I know the answer is probably "no," but I thought I'd ask. Is it possible to keep fit while you are pregnant and not gain weight and lose muscle? I've heard some weird things like that for some women the abdominal muscles can separate so even if you are careful during pregnancy you can lose shape.

OH it is VERY possible to keep in shape, now gaining weight during pregnancy doesn't mean you are going to look like a ball..you can be in shape and gain some weight and still look good. Take walks.
At the gym that i go at two aerobic instructors are currently pregnant both i believe in their 3rd month and they are still teaching those classes, im sure not as hardcore but they're kickin and doing sit ups, even teaching belly dancing classes. SO you can Def stay in healthy shape while still gaining about 10 pounds and ending up looking great. Of course if you eat bunch of junk and don't excercise expect to gain a lot and lose your curves.

Of course you can stay in shape, but let me give you a BIG warning...don't start a new, more difficult program while you are pregnant...only do what you were doing BEFORE the pregnancy and lighten up the high-impact stuff. If your face starts getting beat red, you have gone to far.

I do want to add that just walking is a different issue. If you were doing NO exercise before pregnancy, you can still pick up a walking routine. That is very much encouraged for pregnancy. Be extra cautious and gentle on yourself...your ligaments loosen up and you can hurt yourself more easily when pregnant. It would be a bummer to spend a pregnancy with a handicap because you hurt yourself.

I really REALLY love (and miss) running and was hoping to re-establish it as a lifestyle before I got pregnant, and continue it during and afterwards. This year, I was planning this year to drop about 25 more pounds and do some cross-country. Right now I walk and do pilates (great stuff).

We're doing the kid thing after next year. My husband is wants to do it sooner than later. He says he worries about complications from age (I'm 32, he's 38), but I am healthy and in better shape before my body gets taken over. We went through a bit of a scare from longterm CO exposure this year (long story).

Yes you can stay fit but alot of strange things can happen wile your preg.
My abdominal muscles did separate if you poke my tummy right now you would be able to feel a small space between them. It was so bad were my intestans were sticking out when i would sit up. Now, 2 years later, you couldnt slide a finger through the space you can feel it but its going back.
The more kids you have the bigger chance you have of that happening and once it does happen if you have more kids it will get worse and worse with each one to the point of it not going back with out an opperation.
On top of that I had dibites and was lactous intollerant wile I was preg. As soon as I had her My dibites went away and I could have milk agin though i still dont that much just thinking about what it did to me then freaks me out.

as long as you get into it now yo ushould be able to do it when you get preg unless it becomes high risk.

also when your pregnant and excersizing i dont think your heart rate per min is meant to go above 140, but u should check that with a doctor in case thats the wrong number of beats... also alot of aquatic centres run pre-natal swimming areobics a few times a week