My doctor told me I could travel up to 36 weeks. Just get up and walk every 2 hours. I am 27 weeks and about to take a 700+ mile drive to visit my family. Over 10 hours in a car is not fun, but it's allowed unless your doctor tells you otherwise.
I do not think there is any particular risk as long as you are careful. Remember to take a break every 2 hours and walk for 15 minutes. Remember to drink loads of water (even if it can be annoying because it means you have to pee all the time) and eat a lot of fibers. Water and fibers will help jot to get constipated, which happens often when traveling long distance. And tell your doctor if you have the chance to, if you will see her before leaving. If she has any concerns, she will tell you then. If she says ok, you are good to go. Have a safe trip.