In my training varicosities are usually the result of pelvic congestion. Usually the uterus is sitting in a less than ideal position and blocking the circulation to and from your legs. This often occurs in athletic women, actually, because the uterine ligaments are designed to stretch and the jarring movements of running and such make the uterus bounce around and generally not sit nicely.
With pregnancy, you're adding a giant baby, ect to a uterus that isn't ideally positioned and everything gets more exciting :)
The gentle belly massage can help shift things so that you have as good a position as you can get, discomfort lessons, blood flow improves and life is perfect. ;)
... I just wish I did it more. I have the same pelvic pain that I've helped woman after woman get rid of during pregnancy and do I fix it for myself? Noooo.. *eyeroll*
But I do it enough that I do not have swelling in my feet at all and my uterus sits nice and centered.