what are the main factors?
Well it depends. Pregnancy affects women in different ways.
Near the end of my pregnancies I needed to wee every 30 mins, had a huge unwieldy belly that made me unbalanced when I was walking about, swollen ankles and legs, constant nausea, my blood pressure fell even lower so I felt dizzy whenever I stood up, it was difficult to sleep, and I was just fed up with everyone and everything.
I didn't want to go to the shops let alone the other side of the world. All I wanted to do was stay at home and make it lovely and cosy for my new baby ('nesting' is a common urge in late pregnancy)
Other women will come on here and say they found it all easy and could not only have managed travelling, but would have enjoyed the variety and seeing a different country.
the point is that you won't know how it will be for you, and even if you have had a child before, each pregnancy can be different.
At 32 weeks you could end up giving birth in Japan or the airport or on the plane.