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.