Answer: This is definitely something you need to speak to your doctor about. Generally, women are safe to take a flight up until the 36-week point.
Of course, there are also some points at which it is not necessarily a good idea to fly in the last trimester. This is the case if you have experienced abnormal bleeding, are carrying multiples or are at risk for pre-term delivery.
During your flight it is necessary for you to get up and walk around the cabin at least once an hour. The goal is to prevent blood clots.
While it is generally safe to fly, you want to avoid it as much as possible. It can be risky in the event that you go into labor early.