Usually starting the 7th month travel will not be advisable anymore specially for air travel
Last 1 month I think, or you can get a fit-to-fly memo from doc
Last month dont travel, Ideally last 6 weeks very crucial
My gynae guideline to me is 35 weeks onwards.
Last 1 month might not be safe travel.
first 3 months and last 2 months.
Third trimester onwards
Form week36 onwards