i think the longer you wait for an abortion the worse it is. the bond between the mother and the child DOES start from the tummy, and i think after 7months of gestation the baby COULD live outside of the mother, if i remmeber correctly. so i think the fetus would be like "an almost" baby.
so i think very few, if any, women opt for an abortion lightly, even during the first trimester, and even fewer would do it during the third trimester without a grave medial reason. actually i think at the moment, third trimester abortions are illegal unless the mother's life was in jeopardy (correct me if i'm wrong, but i think even the second trimester abortions need to be accompanied by some medial reason other than "i can't afford to have a baby right now")
my sister in law had to opt for an abortion during the latter part of second trimester and it was a really sad day for all of us. They found irregularities with the baby and said that the mother's life was in danger as well, if she chose to carry the baby to term. after much anguish and soul searching, my brother and my sister in law decided upon a late term abortion -- and after the baby was aborted, they learned that the baby couldnt' have lived anyway because its lungs were misshapen.
this happened about 5 years ago. my sister in law says that she is grateful that they discovered the problem before the baby was born, for apart from the fact that the childbirth might have killed her (!!) she says that it would have been much harder for her to lose the baby after the 2 extra month of bonding.
i certainly wouldn't go for a third trimester abortion if it weren't for a similar medical reason involving life and death. most women who are at the latter part of pregnancy DO want the baby. almost none would suddenly decide to end pregnancy on a "whim" even if it weren't illegal.