F.B.
Most doctors won't let you travel after 36wks, earlier if you a high risk for any reason. What I will tell you, is that even though I don't think airlines legally can prevent you from flying some will give you a harder time than others. I just went to San Diego from 30-31.5wks, so I brought a doctors note saying my due date and that I was fine to fly (and I showed it to a pain in the rear airline worker), so I didn't have to deal with the hassle. Totally would be my suggestion is to get a note, even if you don't "need" it, it's better than having to argue with them.