He committed a crime under Florida law, and he may have to face criminal charges. The mother was 15, he's 18, and that's enough to put his freedom in jeopardy.
In terms of her child, the state will not step in unless there is a reason to do so; her young age is not by itself a reason to remove the child.
In terms of someone reporting a crime, her physicians have a legal obligation to report child abuse (and this appears to qualify as abuse in Florida). However, whether or not an individual physician will actually do so, we cannot guess.
Yup. And Florida is one of the more aggressive states for this sort of thing. There is something of a Romeo & Juliet exception if the minor is 16, but if she's not? All bets are off.

