Hullo!
I have no answer for you (although I seem to remember having read somewhere that stretch marks actually gets less and less noticable during weight loss), but a tip! There is an excellent search engine on this board. I typed in "stretch marks" and came up with plenty of threads:

http://forum.lowcarber.org/search.php?searchid=84327

Best of luck to you!

EDIT: Oh! Potatofree gave you a fine answer. Anyway, I love the search engine. Haven't missed one topic I've wondered about so far. This board is marvellously jam-packed with info from good people. Gotta love it.