I am so envious, I wish I could excerise, but just don't think it's worth the risk. I have high risk pregnancies with vaginal bleeding mainly first trim, but have had bleeding later if we DTD etc (poor DH, but he is getting used to it!!!!)
It would be nice not to be a walking blob of cellulite... I think the worst thing is I am so active before i get pregnant, it is really hard to adjust to doing nothing.
I think yoga sounds great and really good for labouring and keeping you stretchy and supple.