Airline travel/Doctor recommendations

Karina • Child of God. Mother of two. Educator. Excited for what's ahead!
Hi everyone, 
I consulted travel plans with my physician a few weeks back and she told me she'd rather me not travel by flight after 25 weeks, but the airlines allow the mother to be further along. Anyone traveling in the second/third trimester via airplane? What are your doctors orders for travel? Just curious about what other doctors are saying. I'm planning on traveling outside the country to spend time with family before the baby arrives in late May, so I'd be about 28 weeks around spring break, which is when I'd try to travel. Thanks!
Thanks