Alaska Airlines - no restrictions!
PSA - check airline restrictions for third trimester travel before booking a trip! Save yourself some stress!
My husband and I decided to go to San Diego for a long weekend at 34 weeks (I checked with my midwife first, and the flight is less than 2 hours). I booked flights and hotel and then panicked because I remembered that each airline has different restrictions and requirements for third trimester travel. Some want an original and two copies of dr clearance, dated within 10 days of travel between 28-36 weeks. Many restrict travel completely after 36 weeks.
Turns out that I got lucky and booked one of the few airlines with zero restrictions on traveling while pregnant! Thanks, Alaska!