it is better for her to tell her parents now that she is pregnant, than put it off longer.
either way, they are going to be angry, but they have a right to be. they are her parents. if she tells them sooner they can sit down with her and figure out what to do.
is she isnt sure if she is keeping it or not, has she thought about adoption? she could talk about that with her parents, and you could even sit with her while she tells her parents for support.
let her know there are other options out there, and she is not obligated in keeping a child at 13 yrs old.
shes still a child herself.
if the boyfriend is in the picture or not, he has a right to know. but the sooner she tells everyone, the better. yeah, people may be mad, but you can be there like i said for some support.
and if they get mad, its only because they love her[her parents i mean]
just let her know your there for her in whatever she decides.