I think open adoption is a good idea if you feel you cant support your baby or cope etc, but you still want to be in his/her life, see them from time to time and make sure they are ok. That way you can make sure they're happy and safe etc with the adoptive parents. And the baby grows up knowing you're his birth mother, its not a big mystery or secret.
My ex boyfriend left me because he didnt want to be a dad yet (even tho he was in his 20s not a teen). Tried to force me to get an abortion, but I dont agree with those. I kept my son, im raising him without his fathers support, its hard work, some days tougher than others, but I love him to bits and hes changing me in so many ways. Hes my angel =) im glad I kept him. Its best to try at least, because it might not be as bad as you thought.