It is best you get advice from doctor/gynae if you are safe to fly at the early stage of pregnancy. Not all pregnancy is strong and there can be side effects for some mummies esp if their health is not at their best and if you have any medical history. I have fly at 12 weeks for 8 hours flight however it was all good despite not getting any checks with doctor or clearance. But, this is because I know my body well. Hope this helps.
shd be okay I'm at 7 weeks now and just came back last week from overseas.