This is such a great point, I think. What good are moral or logical arguments if they are being made to someone who is so frightened and desperate that she can't even think clearly?
True - and I also believe it's more than just an inability to think clearly. There may be no support system. She may not know how she will support a child. She may have a boyfriend who wants no part of it. She may have parents who would not be supportive. Abortion may seem like the only possible exit for what feels like an impossible situation.
Someone coming along and saying, "Oh, by the way, if you do this, you're going to hell" is probably the least of her worries - but someone coming along and offering help may be able to make a difference.