How do you know if you're pregnant?

My friend is 13 years old and she had sex with a 15 year old guy. She had gave him head,she got fingered and has a hickey.She started at 4:30 and was said to be done at around 5:00 in the morning and I am really worried about her will you please e-mail me back with some really good advice about what we should do we are not sure if she is pregnant and symptoms and signs on how to tell if she is pregnant.plus her parents don't know about it yet so should we tell them or have her do it.you can e-mail me at Fun mail me

why would she have sex at 13?

if she is vomitting and her health seems a little abnormal, it's possible. also ask her if the boy had used a condom, if not she could have aids if he has it or she could be pregnant or even both!

What the hell she thinkkin?? 13 years old!! shouldnt she be gettin ready for school or sleepin that early in the morning??