"Short Distance" Travel During Pregnancy

I am just curious when the group thinks or has been told is the time you should stop traveling even short distances(2-4) hours by car. I travel around the state for my job and have a big event the first week of October which would require me to stay a couple nights about 3 hours away from my house. I will be 35 weeks. I plan to ask my doctor next week to get the answer that is best for my pregnancy and medical care. However, I am just curious on what the group has been advised to do.