If her pregnancy test came out positive well guess who's an auntie.
Enough with the jokes, back on the subject.
But I think its a good idea that your sister is staying with you, let her have her own choice if she wants to keep the baby or not.
But also does she know how much money it costs to raise an infant in today's world? A lot. Tell her if she wants to keep it, but finish school and give the baby up for adoption is also another option too.
very slim chances of teen moms opt to go with carrying the baby to term and then putting it up for adoption, then go back to school to finish.
Abortions in my opinion are very easy, if you feel you can't carry this baby to term then go ahead and go with the abortion. But that's in my opinion too.
I hope with what ever choice your sister makes she will be happy.