I went on a 3 hour flight when I was 10 weeks. My midwife had no problems with it. Just said to not walk threw certain xray machines
This might help you clarify. It's kind of all about comfort in travel, and not safety.
In the first trimester, mothers are more likely to feel queasy and nauseated during plane travel. Not a safety factor, but just a comfort thing.
http://traveltips.usatoday.com/safe-travel-during-first-month-pregnancy-1564.html
I don't know where you're getting this information Smile, but in general you can travel until late pregnancy. Almost nothing you do in early pregnancy makes a difference on whether you miscarry or not, and there's nothing doctors will do for you if you do start to miscarry before 14 weeks.
My Doctor said if I wanted to travel I'd have to be atleast 14 weeks before I can and then when I get to 37 weeks I wouldn't be able too
My doctor told me I can travel how ever I want until im 34 weeks.