in most cases, if its a single and non-complicated pregnancy, you can travel onboard up to the 32nd week with just a doctor certifying that you r fit to travel. from 32nd to 35th week, you will need a doc's med certificate as well as the airline's approval. beyond the 35th week you cannot travel. i should know cos i took my wife back home at 28 weeks. Visa by default you can extend till 6 months. the immigration captain almost always grants a 7th month extension. captain can again authorize extension till 8 months but most often they will reject the extension. i would say it's best to travel before 28 weeks though.. all the best