Ask your OB for a prescription for "real" compression stockings/pantyhose. You can get them at a medical supply store. I had to get them for flying while I was 26 weeks pregnant, and the ones they sell at regular clothing stores aren't the same. Compression stockings vary by compression and size, and the salesperson at a medical supply store will measure you for the correct fit. They're more expensive, but, in my case, were 100% covered by my health insurance since they were prescribed by my OB due to pregnancy and I needed them due to a medical issue (i.e., preventing blood clots).