It is more difficult to travel during the third trimester than the earlier two. You don’t have to be scared of anything, but your doctor’s advice is an imperative.
This is why it is necessary for you to choose your destination wisely. It should be some place where you will not have to walk for a long time. This is the time for you to relax, eat well and, generally, take things slow and steady. Remember to choose a location where there is a hospital close by. In case of an emergency, you should be able to reach the hospital quickly.
Yes, it is safe to travel by air during the third trimester but the doctor will advise you to avoid travelling during the final month. His/her reasoning, as common sense will tell you, is that the chances of you going into sudden labour are most likely during the last month.
When you do travel by air, remember to sit on the aisle seat. You should be able to stretch on the seat. Of course, you should able to do it with a cushion supporting your lower back like in the second trimester. Also, some airlines have specific rules about women travelling during the third trimester. Check those out. Carry some food to meet your cravings and pangs of hunger. In any case, walk a wee bit every one hour for blood to circulate.
Do not forget to consume water as much as possible for rehydration. Carry your own water instead of depending on outside sources which may not be clean and safe. It is very critical to maintain good health during this phase. Water will also help control the swelling on your feet and ankles and prevent blood clots.