I flew when I was about 8 or 9 weeks pregnant Brisbane to Melb and the most unsafe thing about the flight was THE FOOD on the way home they served this DELICIOUS lamb dish I love lamb.... baby does not love lamb, that is the only time in my 19 weeks i have actually been sick.
I think domestic flights are fine at any time it is just long distance or flights in teeny tiny planes that are a worry.... not 100% on that though.