Congratulations!
I rode comfortably through my pregnancy. I was able to wear my bike shorts throughout, especially the ones with a drawstring - I just tied them up under my belly. I also found an XXL women's jersey super clearanced out at REI, so I bought that and had plenty of room. It really wasn't a big deal.
That said, I'm no racer/club rider. I don't think I cracked 20 mph past my first trimester. But if you don't have any complications, there shouldn't be any reason for you to stop riding, as long as you're taking care to ride safely. When I brought it up to my OB, she said that she thought cycling was great for me and I should do it as long as I feel comfortable.
If it feels good, and it makes you happy, I say go for it!
2007 Trek 5000
2009 Jamis Coda
1972 Schwinn Suburban
"I rejoice every time I see a woman ride by on a bike. It gives her a feeling of self-reliance and independence the moment she takes her seat; and away she goes, the picture of untrammelled womanhood."
Susan B. Anthony, 1896