Why is it that women are more likely to get blood clots on an airplane then men?

Clots: Not unless you are taking ocps.

The real issue: As dr. Mahajan said, hormones can increase risk but the real issue on a long flight is movement. If you are on a long flight and don't move, you have an increased risk of getting a blood clot, whether you are male or female. Wearing graduated compression stockings (not teds) can help but the most important thing you can do on a long flight to decrease you chance of getting a clot is to move.