That was a very irresponsible thing to do at 13. She has a good chance of getting pregnant ANY time she has sex. She shouldn't be having sex at 13 because SHE COULD END UP PREGNANT!!! Tell your friend that if it has been within 72 hours of having sex that she can take plan B, but she'll need a prescription for it or she'll have to go to a planned parenthood. If it has been longer than 72 hours, she's going to have to wait until her period is late and take a test. If she does get a period, then she needs to go straight to her doctor or a planned parenthood and get on birth control and stock up on condoms and spermicide. And she has to USE them every time she has sex!