Well at least she's told you and it didn't just pop out on the couch!
As other have said- get it confirmed, make an appointment with GP, find out how far along, ask about the dad.
There will probably be a specialist teenage pregnancy midwife or nurse she can see.
There may be a brief social work investigation depending on the wider circumstances.
Ask her if she's been drinking smoking or taking drugs.
Give her vitamin d and folic acid.
Talk to her in the most impartial way about the options of keeping the baby, having an abortion or adoption.
Tell her it's her decision but you will support her no matter what (even if this isn't how you are feeling).
Say you want to meet the boy.
Ask her what she intends to do about school and find out if there's a mother and baby school unit in your area.