Here's a site with some information and links to other sources of info. It's mostly about PIH, but I think there's some things that are relevant for you.
The other thought that came to mind, is what size cuff are they using to check your blood pressure? If you have larger arms, the regular cuff can artificially inflate your blood pressure readings. Make sure they use the large size cuff for you. I know I've had to ask a couple of times, and some of them get a bit pissy about it, but it really does make a difference.
http://www.plus-size-pregnancy.org/lgbpcuffs.htm
The main index for that site is
http://www.plus-size-pregnancy.org/firstindex.html , it's a great resource.