How to surrogate without having a prior child?

I want to become a gestational surrogate mom. I'm 21 and completely healthy. After researching, I found that you cannot do this if you haven't had a child. I can kind of understand why, but I don't think I would want to do this after I have my own child. And I would want to do it now, before I start a career. Are there any programs out there that doesn't require you to be a prior mom?