I was told at my over due appointment when i was pregnant that if you are going to get stretch marks then you will. He said its hereditary, i dont believe that bit as my mum had 7 children, no stretch marks. I got them with my 1st! I have however read that its to do with not having enough zinc in your diet. So maybe a good healthy diet will help.
The creams cant harm can they, do what ever is necessary. Prevention is better than cure after all in this case