Generally, air travel before 36 weeks of pregnancy is considered safe for people who aren't dealing with any pregnancy problems. Still, if you're pregnant, it's a good idea to talk with your health care provider before you fly.

Your provider might suggest that you not fly if you have certain pregnancy complications that could get worse because of air travel or that could require emergency care. Examples include a history of miscarriage or vaginal bleeding, severe anemia, and high blood pressure or diabetes that's not well controlled. If you had preeclampsia during a previous pregnancy — a condition that causes high blood pressure and extra protein in urine — flying may not be advised. The same is true if you're pregnant with twins or other multiples.

Tell your provider how far you are flying, as the length of the flight might make a difference. Also, be aware that some airlines may not allow pregnant people on international flights. Check with your airline before you make travel arrangements.

After 36 weeks of pregnancy, your health care provider may advise against flying. And some airlines don't allow pregnant people to fly after 36 weeks. The airline also may require a letter from your health care provider that states how far along in your pregnancy you are and whether flying is advised.

If your health care provider says it's okay for you to fly, and your plans are flexible, the best time to travel by air might be during the second trimester. The risks of common pregnancy emergencies are lowest during that time.

When you fly:

• Buckle up. During the trip, keep your seatbelt fastened when you are seated, and secure it under your belly.
• Drink plenty of fluids. Low humidity in the airplane could cause you to become dehydrated.
• Avoid gassy foods and drinks before you fly. Gases expand during flight, and that could make you uncomfortable. Examples of foods and drinks to avoid include broccoli and carbonated soda.
• Think about medical care. Plan for how you'll get obstetric care during your trip if you need it. Bring copies of your medical information in case you need care while you're away.

Blood clots

Air travel can raise the risk for blood clots in the legs, a condition called venous thrombosis. The risk is higher for pregnant people. Moving your legs may help prevent this problem. Take a walk up and down the aisle every hour during the flight. If you must remain seated, flex and extend your ankles from time to time. In general, it's best to avoid tightfitting clothing, as that can hinder blood flow. Wearing compression stockings can help with blood circulation during a long flight.

Radiation

Radiation exposure linked to air travel at high altitudes isn't thought to be a problem for most people who fly during pregnancy. But pilots, flight attendants and others who fly often might be exposed to a level of radiation that raises concerns during pregnancy. If you must fly frequently during your pregnancy, talk about it with your health care provider.