Back in the day when I was super active on a Health and Fitness message board, there was a poll about running playlists. Someone mentioned the Dancing Till the World Ends song by Britney Spears, but said that when they sang along in their head they would always sing "Running Till the World Ends" instead. I went and downloaded that song and found it to be incredibly catchy - bonus that it has a great beat for speedwork.
I have no plan to stop running (or kettlebell training, but that's a different post!) during pregnancy. In fact, my (potentially unreachable) goal is to stay in good enough shape that I'll be able to participate in some way in the 2013 15th Annual Flying Pig next May, when I'll be about 37 weeks along.
The general rule of thumb when it comes to exercise is to not start anything new. Luckily for me, I've been running regularly for a while now. In fact, I ran the day before I got my BFP and two days after. I also ran yesterday morning and will go out again tomorrow morning. Have to take advantage of this amazing fall weather while I can! I'm not running long right now, mostly due to the fact that it's really dark when I run before work and I'm wary of straying outside of my well-lit neighborhood. When I have my first OB appointment in a few weeks, I'll definitely ask what they think is the upper limit for mileage. It would be fun to run/walk a half marathon - I see pregnant women out on the courses all the time. Then there's the girl who "ran" the Chicago Marathon at 39 weeks - that's hardcore. I would LOVE to be in that good of shape at the end of this pregnancy.
To be honest, I'm more concerned with running while breastfeeding. Nursing boobs are no effing joke.