This is her choice to make, not yours. You really just need to be supportive of her.

you just have no clue. this girl has a history of mental illness and drug use.i do want ot be supportive but i mean this is just so bad.

Chances are, she's too emotionally close to this to see it clearly. Telling her this is a bad idea or to get an abortion won't do anything except upset her and make her angry with you. You may think you're right and she's not (and that might be true, I don't know) but you need to understand that this is her life as she knows it. She loves this man and is excited about her pregnancy.

Instead of trying to hammer it into her head that she's making a mistake, be there for her. Things will probably get worse for her, and instead of saying "I tried to tell you", just be there to catch her when she falls. Even if you can't bring yourself to support her, just let her know that you'll always be there if she needs a friend.

If you're worried for this baby, however, it's probably in your friend's best interest for you to ask her to stop using drugs. Print out some information online about drug use and pregnancy, newborns born with addiction problems, birth defects, and behavioral problems. Present this information to her with an "I'm just trying to help you make some good choices for your baby" attitude, not a "you're doing wrong and you're being a bad mother" attitude. She'll be more likely to listen if she feels you're her friend and not judging her. Also, you might want to keep in close contact with her after the baby's born. If you think her and the father are using drugs around the baby or that they're in the house, an anonymous call to CPS might be in order.

These are ways that you can help your friend without pushing her away. You can't fix this for her, mainly because she doesn't want this to be fixed. If you're looking for advice on how to get some sense into her head, I'm afraid that's going to be hard. She's going to need to learn this lesson on her own, and it's not going to be an easy ride. She needs strong, reliable friends around her right now.

This really isnt a situation where you have a say though..
shes made up her mind, and as long as she is open and honest with her doctor about her past mental illness and drug use, they can help adress the situation for her.
If this is a bad decision, which you think it is, she'll have to figure that out for herself...for all you know her bf could do a 360 from this and shape up and be really supportive for her.
Alot of teens get pregnant younger than this and keep their babies.
In my pregnancy book, it says that there are some drugs that after many years of use during pregnancy, have shown no evidence to suggest that they may be harmful to the unborn child[this doesnt mean its ok to do still]As long as she consults her doctor for info on drugs she has used they can help her with recovery and withdrawl progress.
About the mental illness, again she'd have to tell the doctor to seek more information about it while she is pregnant.
All you have to do is try and be supportive...

honestly, all you can do is support her. I'll tell you what happened with me and my best friend.. she HATED my boyfriend like no other person could hate someone. I took a pregnancy test so I could re-up my birth control. And it came out positive.. at first she was the most supportive person there was. We talked on the phone. But she would try to steer me in the direction of abortion. I knew the choice was up to me and I was going to keep it with the support of my family. We didn't talk for one weekend, just because we went our seperate ways. Next thing I know, I'm having a conversation with her and she's screaming at me telling me that we won't be friends anymore cause I'll have a baby and she'll be embarrassed to go out with me because i'm pregnant and then she crossed the line when she told me that i had to get an abortion simply because my baby would be hideous... so yeah my best friend of 3 years isn't my friend anymore, honestly just support whatever path she decides to take and realize that she's going through more pain than you could ever imagine.