Would you tell her parents?

Pip • Pregnant with a little boy • c-section is booked for 4th July 2016 at 8am ✨
I have a best friend who has changed all of a sudden. I'm 19, pregnant with my first so I see her behaviour as immature and crying for help. But I feel like I can't allow her todo this to herself. She never drank or took drugs before.. 
So now she's met this waist of space who has no job and sniffs and smokes his money. She's really interested in him and does anything to please him.. Since knowing him, she's lost her job due to not turning up, taking out loans £200 a time and spending it all on weed and alcahol. 
Her parents are very wealthy and have brought her up very well, to live a life better then this. She's just partying hard every night. She had a new job to attend today and I asked how it went and her reply was "I never went I was too hungover, didn't stop drinking until 6am" 
Her parents have messaged me privately on Facebook in the past few weeks asking about this guy and what she's doing and I've not said a word as I was loyal to her. But I feel like I can't watch her do this to herself anymore, he's out of control. She's even trying to get herself pregnant behind this guys back which is beyond crazy!!! 
Please help and advise me...