I flew past 8 months pregnancy--flight was only 2 and a half hours. I required no documention for Delta when I flew. My doctors were like "whatever floats my boat". But I was low-risk. If you have medical conditions in your pregnancy, that might prevent you from flying. It is up to individual airlines. I found 3 airlines below--and each of their policies is different. But I think you will have to change your cruise.
Delta
Pregnant Travelers
We do not have travel restrictions for pregnant women traveling on Delta's domestic and international flights. You do not need a medical certificate to travel.
Ticket change fees and penalties are not waived for pregnancy. Therefore, if you are traveling after your eighth-month, we recommend that you check with your physician to make sure you are physically fit to travel.
Northwest Airline's
Flying during pregnancy
It is commonly recommended that women not fly at all during their last six weeks of pregnancy. Northwest Airlines' policy states that pregnant passengers traveling within 30 days of expected delivery must provide a doctor's statement dated within 72 hours of departure indicating the due date and indicating that air travel does not pose a health risk. Women in labor will be denied boarding for safety reasons.
Pregnant women should always consult their obstetricians or midwives before traveling. Traveling during the second trimester of pregnancy is often easier as morning sickness will most likely have subsided, energy levels are up and you are still a comfortable distance from your due date. Here are some additional tips for staying comfortable on your flight:
Reserve an aisle seat so that you can easily access the bathroom and move about the cabin. Getting up and walking regularly will help combat swelling and discomfort.
Bring a copy of your medical records and ask your doctor for a referral in case of an emergency while you are away.
Wear comfortable, loose-fitting clothes and flat shoes. Wear layers if you are prone to body-temperature fluctuations.
Keep your seatbelt low around your hips, not around your abdomen.
Get a small pillow from the flight attendant and place it under your lower back to avoid back strain.
Drink plenty of water-at least one liter for every two hours in flight
American Airlines
: What are the guidelines for traveling on American while pregnant?
A: A medical certificate is required if travel is within 4 weeks of the delivery date in a normal, uncomplicated pregnancy
For domestic flights under 5 hours, travel is not permitted within 7 days before and after the delivery date. If you should need to travel within 7 days before or after delivery, a medical certificate is required as well as clearance from our Special Assistance Coordinator.
For International travel or any flights over the water, travel is not advised within 30 days of the due date, unless the passenger is examined by an obstetrician within 48 hours of outbound departure and certified in writing as medically stable for flight. Travel within 10 days of the due date for International travel must have clearance from our Special Assistance Coordinators. Travel within 7 days after delivery requires clearance as well.
For more information, please contact a Special Assistance Coordinator through AA Reservations at 800-433-7300.