My blook pressure was high in the last trimester for both of my girls. My doctor actually said I did not have to cut back on sodium, because she said it was more about the pressure that the baby was having on my body than what I was eating. She did have me try to stay off of my feet as much as possible for a couple weeks, and after that didn't help a whole lot, I was on full bed rest for the last week for both of my girls. My first was induced (and we ended up having to have a c-section), and then my second was a c-section. My first had to come a week early and my second two weeks early, but they were both big babies and very healthy.
One of the best things I was told was to lie on your side, and I think one side is better than the other, but I can't remember which. I bet if you do a search on the internet you might find the answer. Even if they haven't put you on bedrest yet, it will help if you still try to take it easy and lay down on your side whenever possible.
Regardless of what all of us say, just follow what your doctor says, and don't worry too much...that will just make it go up more. :) Also, I do remember being told that at that point in your pregnancy it won't hurt the baby, but it is just your health that might suffer. So take care of yourself, relax, and be glad you are so far along. HTH.