My best friend's missed her period again

She's been having sex unprotected with at least 3 men recently, I've told her how unclean and dangerous this could be, she's missed two periods and is refusing to face the facts.
There's so many dangers that come with unprotected sex how should I convince her to a) take a test
B) get herself checked out
She's only 19, why is she doing this to herself?

she's trying to grow up too fast.

some females like the thrill of having sex without a condom. yes this is dangerous and yes you should convince her to take a test and if she is pregnant and carries it to term she should make a list of the 3 guys she slept with (or more if she did) and get a dna test to find out who the real father is. also suggest to her to see a doctor and get checked out for stds because if she decides to keep the chils and if she has them then when she gives birth thoose stds could be carried along with her child...its also better so if there is a treatment or sure for one she has they can fix it before it gets worse.

as princexx has said, it seems that your friend loves the thrill of it all... and dosen't think straight, when it comes to her safety... as much as you try to tell her she's pregnant and still denys it, it's most likely cause she's scared you're right, she knows you're right, or she hates herself for not listining to you earlier!! try to get different friends to convice her into seeing a doctor and getting herself tested (better now then later!) - if she dosen't listen to you, maybe she'll listen to someone else! - I sure hope she dose! good luck =)