If you’re experiencing a healthy pregnancy, it’s generally safe to fly until about 36 weeks. Most airlines in the United States allow pregnant women to fly domestically in their third trimester, however some international airlines restrict air travel after 28 weeks.

You shouldn’t fly if you have serious pregnancy complications, like preeclampsia or a heightened risk of preterm labor.

Of course, always check with your doctor before flying anywhere during pregnancy to confirm it’s safe for you.

By the way, certain airlines may require a medical certificate from a doctor if you’re in your last month of pregnancy. Call your airline ahead of time to find out its official guidelines on pregnancy and travel and what documents you may need. (Heathline published a handy chart detailing airline-specific policies.) And don’t forget the compression socks!