
a lot of women get swelling in their lower extremities late into pregnancy. It's just the nature of blood flow, vs the veins being weakened by progesterone, and total blood volume. If she has swelling just there, I wouldnt' be TOO concerned with pre eclampsia- which normally exhibits when swelling of hands and face is fairly extreme.
She can wear compression socks (or good support hose) that you can get at any pharmacy. A pharmacist can show you where they are if you don't know what you're looking for. That's what I have to do as I have terrible varicose veins in my right leg, and wear support socks so my leg doesn't look like an elephant's by the end of the day.