I have a 13 yr old granddaughter and although I can't imagine her having sex at this age, especially since she is almost always with her family or in school, there would be serious family intervention but I'd avoid any contact with the legal system.
OTH, I've known people who married at 13 and lived a long prosperous life and raised children and had grandchildren and great granchildren, but that was another era.
I spent last night speaking to a criminal client who had her first child at 13. She grew up in the bad part of time that is over run with drugs. The life she has lead, she is 24 now, is one so desperate, that it could have occurred on another planet.
I have been a prosecutor for 13 years and a defense attorney for 13 and thought I had pretty much seen it all, but I was wrong.