I don't know what the laws are in Alaska, but I'm pretty sure a minor can't get an abortion there without parental permission. So she's stuck with the kid. One part of me says fine, her parents are well off and well-connected and they can afford to support another baby. Another part of me is sad for the baby, who will go through life being the national poster child for bad parenting.
Edit add After doing a little research, it turns out the age of consent in Alaska is 16, and the 1997 law which required a parent's permission for someone under 17 to get an abortion was overturned last year, with no new law taking its place yet (ironically, Palin refused to allow the bill, which she supports, to be introduced in a special oil-related session of the Alaska legislature last Spring). So as far as the law goes, Bristol's decision to have the baby vs. having an abortion was her own choice. As far as Real Life goes, well, who knows?