why not give them the option of sterilization
because it's irreversible, or close to being so. as far as i know, it's not illegal and accessible to anyone who wants to do it now. if it's easy and cheap, and so convenient, why do you think it's not more widespread already?
there's teenagers who already have a negative view of responsibility
well, since you'll already be giving them a responsibility test in order to decide whether they should be sterilized, why not share the results with the DMV? It may save some car accidents in the future. Maybe a future employer, too? So they don't get hired, by any chance. And while you're at it, the banks, so that they don't get a loan they might not be able to pay off. Or a potential boyfriend or girlfriend, so they know what they're getting into ahead of time... Actually, we might just give them armbands to wear at all times, so that we all know who they are!
People should be free to make mistakes in their lives. That's what life is about - learning, growing, gaining experience, and passing it on.