Flying During the Third Trimester May Be Prohibited or Regulated
The reasons for these restrictions on flying during pregnancy, are many but the logical and simple answer is that the airline (and you) doesn't want to be in the habit of delivering babies while flying over the Atlantic. In addition, there are many medical and health reasons why it is logical to put aside the thought of flying. Just what are those rules though about flying during third trimester, what is the answer to "Can I fly during my third trimester?" and what should you do if you are permitted to fly?
First let's talk about what the general practice is for most airlines. Most airlines will permit you to fly up to your 36th week. In some cases they will ask for a note from your doctor. In other cases they won't ask for anything. The rules change if you are having multiple births. In that case, most airlines will let you fly up until your 7th month. Even though this is the general rule you would be wise to call your airline and ask for the airlines specific rule and come with a doctor's note even if they don't mention you needing it for boarding. Better to be safe than sorry. If you have had any difficulties with your pregnancy such as high blood pressure or other symptoms you will not only want to double and triple check with your doctor but you might also think twice about flying even if you are given clearance.
Keep Flights to a Minimum After the sixth month of pregnancy.
If you have a choice regarding when to fly, the safest time is during the second trimester. The second trimester is the time you and the pregnancy are at its most stable. If you don't have a choice and you find yourself on a plane flying during the third trimester there are a number of things you can and should do to keep yourself and the baby healthy. Remember the air in a plane is notoriously germ filled (re-circulated air) so make sure you are in good health and stock up on that vitamin C. When you sit, make sure you belt yourself nice and low. Also make sure you have on loose clothes and shoes since there is a good possibility that you might retain a bit of water.
Once the plane has leveled and the seat belt sign is off think about getting up when you can to get a little circulation. Pregnant women have a greater risk of DVT (deep vein thrombosis). Passengers in planes already run this risk; it is higher still for pregnant women and moving around helps reduce that risk. Since you're going to be getting up a lot ask for an aisle seat or a bulkhead seat so that you are free to come and go without feeling badly about asking fellow passengers to move.
Drink, drink, drink. Water that is!! Stay hydrated. Since you have an aisle seat and you need to move around anyway it won't matter if you have to go to the bathroom many times. You need to stay hydrated since airline flights always dehydrate and a pregnant flyer gets even more dehydrated so drink plenty of water.
For all things that you want to do during the third trimester there are a few simple rules of thumb. First, if it feels like it might be too much for you it probably will be. Second, make sure you put yourself in the most comfortable position you can find and third, don't do anything even remotely risky, including flying during the third trimester, without talking to and getting the okay from your doctor.