Im due to fly next week, i asked my midwife if all was ok to fly she said no problem at all. As far as I am aware flying does not increase the risk of miscarriage, chances are at 10 weeks if your boby is going miscarry it will, my midwife said "you cant knock a good apple off a tree"
I aggree with becky that you should check with your doc or midwife, just to be on the safe side, no point in risking something if you can help it.
Natalie x