That's what regular birth control does.....the Plan 'B' pill is extra strong female hormones, you can take if you have sex one night and go oops, I think I forgot something...take the pill and it reduces you chances of getting pregnant more than those chances already are.
It doesn't kill the fetus (it is not RU486). And it may not 100% prevent a pregnancy from occurring...but that's the intent.
Things that interfer with the implantation of a fertilzed egg.
These are things millions of women use on a daily basis to prevent themselves from getting pregnant.
I have no problem with plan B cause all it is is Hormones.
1) Some people consider a fertilized egg to be as valuable as a fetus.
2) Plan B can prevent a fertilized egg from implanting.
3) Thus, to these people, the "killing" of a fertilized egg (not allowing it to grow) is as bad as the killing of a fetus, because they are of equal value in God's eyes (or Allah's, or whom or whatever's).
I hope that helps you see why some say Plan B causes an abortion, because to them, it is an abortion.
Zissou-- I think you are right. Middle-to-upper class parents and teenagers see pregnancy as a disaster, one that will disgrace the family and prevent the mother from going to college and "making something of herself." Middle-to-upper class families also have better access to healthcare, and assumingly, birth control and abortion. It would make sense that we don't see as many middle and upper-class pregnancies because of these factors. I sincerely doubt that working class and poor teenagers have sex more often. I might buy that they have it earlier, but once high school hits, I doubt there is much of a statistically significant difference.