kids, sex, and birth control

I was having a talk with one of my friends the other night... She is a Christian... Her husband left her a few years ago for another woman... and she is raising a 13yr old daughter all by herself. The dad... is gone... he doesnt want anything to do with the family now. Anywho... I was talking with her and we were talking about kids having sex. (obviously before marriage)
She said she was thinking about IF her daughter came to her and said that she was having sex... she would immediately get her on some sort of medical birth control (pill, patch, ring etc). And have a talk with her about sex, (again) the risks, and God. But she would definetely put her on birth control... just in case.
She was telling me her reasoning behind this.... if her daughter is willing to go out and have sex at least once.... there is a chance that she might do it again... (boys are very persuassive) and she would rather her be protected so there would be no unwanted pregnancy. Her cousin found out a month or so ago that their daughter had been having sex, got pregnant, and had an abortion... all with out her mothers knowledge. She found out from the mother of her daughters friend. The mother overheard the girls talking and called shortly afterward. She had told the mom that if it were her daughter, she would want to know. The cousin confronted her daughter about it and she just said that she was scared. She was 16 and wasnt ready for a baby and knew that they definetely couldnt afford to raise a kid. So she thought this was best. She hated herself for it, but didnt know what else to do.
My friend doesn't want be put in this same situation...
So I asked my friend... Dont you think that putting her on birth control (that can fail~i have proof!!) is kinda like saying.... well, i dont want you to do it... but here go ahead.

What is the right thing to do? In todays soceity more and more youth are having sex younger and younger... I was one of them. I was also one of the very lucky ones and didn't get pregnant till I was an adult (or mostly) and had a full time job and was able to take care of my son. (I also had a great boyfriend who stayed with me and was a great father and still is). But what is the right thing to do? Prepare them in every possible way... show them right from wrong... tell them what the bible says...what God says... but also prepare them for IF they decide to go out and do it too? I honestly don't know the right answer... I don't know what I am going to do when I am faced with that situation... What do you think is right? If it were your daughter... what would you do?