I had to have an abortion when I was 21. I was living in a refuge, had no income or employment, and was studying full-time whist dealing with my mentally-ill mother. Before any comments of "You should have used birth control" are thrown at me - I was on the pill. The biological father would not help. It was the toughest decision I have ever had to make. Selfishly - I wanted nothing more than to keep the baby. But I knew that I was in no way capable of doing so, and it would have been cruel to have kept it.
I still think about what may have been, but I know that I made the right decision for the sake of the child - which surely is a mother's job?
Some women may not feel guilty - and that's okay too. Until you have had the misfortune of having to make the choice, do not fool yourself into thinking that your opinion is relevant.
Even though you might say it's just a bunch of cells. So were you once when you were inside your mother's womb. Would you want to know that your mother agreed to kill you when you were a helpless, unborn baby. Of course they do. Abortion is basically murdering a helpless baby.
The definition of birth is giving life to a baby. Giving life, therefore, before birth, the fetus is by definition, not alive. How can you kill something which isn't alive? In fact, in the countries where abortion is legal, it only allows the woman to have an abortion before three months, so the fetus is barely formed, so it's not really a baby.
Plus, do women who abort feel guilty later? Imagine this, you are a woman and you were raped, and months later you find that your rapist has gotten you pregnant. Would you feel guilty if you aborted then, if you chose not to bring to the world a rapist's son/daughter? I don't think you'd be guilty if you aborted at all, in fact, you would be relieved.