Should be OK if your MW thinks that it'd be fine. Make sure you get up and walk for a little bit every hour to keep the circulation going. There's a risk of clotting if you don't keep active at that altitude I believe. Also worth investing in a pair of those travel socks for pregnant ladies/ old people as they can help prevent DVT! Good luck!
I flew to Costa Rica and managed.
Just make sure you walk often and if possible get the seats next to you so you can put your feet up. Good luck!
I've flown several times while pregnant, late 2nd trimester. i wasn't particularly uncomfortable. Just make sure to move around, and try to avoid the backscatter screening machines; i don't trust that level of radiation on baby.