I dare not just tell you to get used to it! I think pretty much everyone gets 'fuller' thighs when they're pregnant (perhaps not Nicole Richie but she's a human pencil!).

I rode my bike everywhere right up til the day before I went into labour and even when the gears broke and it was stuck in a high gear, I still rode it (still haven't had the bike fixed either!).

Biking is (also) great as it shifts your growing weight and center of balance into a different position to walking and lets your tired back have a break. It also takes the strain off your feet which might get a little fat and fluid filled towards the end.

Good luck,
A