Answer:
The vast majority of abortions are performed before the fetus has developed a nerve system, therefore they are not cruel since the fetus cannot feel pain or fear.
The life and choices of an adult woman should come before the life a fetus, especially one that isn't developed yet.
Carrying a pregnancy to term can permanently change a woman and she should be
allowed to prevent this if she so chooses.
As far as the mother's health, abortion is safer than childbirth and as safe as having dental work.
The planet is already over-populated and there are not enough parents to adopt all the unwanted children.
Sometimes birthing a child would damage the mother, either physically or psychologically.
More info here if you're interested at www.naral.org