I know a lot of people swear by Runningskirts.com, and I love them, but I've never run in them pregnant. That also doesn't help you for your half this weekend, so. I'm not helpful.
I would just go buy a size up in your favorite pants. Everything I have looked at hits under the belly, which would not work for me at this time. I know I bought two pairs at Pea in the Pod last pregnancy, but can't remember the brand...
Re: Maternity Running Pants