It’s really, really important to recognize that when you think you see a young mother, the last thing you should be doing is scolding her for having a kid. There is just so much wrong behind doing that, like being sexist and punishing women twice over, but that’s not all there is to it.
The las thing you need, the worst thing, of course, is if you turn out to be wrong. Read this and see how that would play out.