I work with a lot of these women and their children. They don't learn, or won't. Oh, maybe having 4 at one time would be a wake up call to some of them, but most just keep having babies by different fathers and let other people be responsible for them. Now keep in mind, that I am working with the ones who become a problem. In my experience, the ones that learn don't end up on my caseload. It is very rare, however, for all the children of these women to all have the same father. Sometimes they pay support and sometimes they don't. Sometimes these women get fixed. Often though, they raise kids that just repeat the cycle. And the children in these "families" are becoming sexually active at ages that would shock you.
As do I, but my work is waaaay after the fact. Waaaaay after. I see the personal and interfamily damage and how it all gets passed on to defenseless children.
I'm convinced that prevention is key.
First illegitimate child - mandatory Norplant implant and "probation"/counselling.
Second illegitimate child - mandatory tubal ligation.
In your case load of girls have been pregnant way too early and seem to be looking for a man to fill that 'empty space', have you seen any of them with caring fathers of their own?
My premise is that it isn't as much the mothers of these girls who are letting them down as it is their own fathers. Without the love of a father, a girl will try to find that love elsewhere.