Yes - they can say no at the gate. I had a friend who was flying when she was 34 weeks. She had a note from her midwife stating how far along she was and that hers was a normal pregnancy. On her return flight, which was 2 weeks later, they told her that 1. The note was only 'good' for 1 week and 2. that now she was 36 weeks and they don't allow women that far along on the airplane. I don't remember the airline, but I know she had to switch her flight to the next day because they actually made her go see an OB in their city and get a note from him!!!! Madness, I say!!!
Just check, check and double check. When in doubt, wear a big coat and if anyone asks if you are pregnant, just scowl at them and say "HOW RUDE!!" very loudly
