C.P.
I love this question.
You cannot prevent stretch marks and you cannot make them go away once they've arrived. They will fade with time, but never go completely away. You may be able to lessen the severity of them with good hydration (drinking water), but you cannot stop them from occurring. Some are more prone to them than others.
A stretch mark is a tear in the dermal and endodermal layers of the skin. The layer you put lotion on is the epidermis...but that lotion never affects those "underlayers." So no matter what you read in magazines and such, there is no lotion out there that will stop them or make them go away.