In not positive it's true or not but I don't think it's a good idea.i had 2 cousins miss carry flying. One was 8 week and the other was like 7. I'm not site of it was the flying that caused it. You should talk with your dr.
My doctor told me that first and last trimesters are not safe. He said between 15-25 weeks are actually the safest time for flying if you have to. Also, if you tell the flight staff that you are expecting, they can refuse to let you fly without a doctors note.
Ive heard that flying is not really dangerous in the first trimester. Its mainly due to feeling uncomfortable with morning sickness that could be the main culprit. If your doctor thinks you are healthy, you can fly. The second trimester is the best time to fly tho. After 28 Wks no flying is permitted/advised due to early labour/extra risks. Ive just recently returned from a 9hr flight at 7-9 weeks and apart from nausea, all was fine. I just made sure i moved/walked/stretched a lot during the flight and took it easy. Hope this helps.
I flew to hawii from Florida my first trimester my daughter is now 9 years old and healthy no damage done :)