Utilitarianism
Is teleological, concerned with outcomes. Utilitarians would ask whether having an abortion brings about the greatest good. Having an abortion because of financial pressures, other family members' needs, education, work - any of these reasons may be justified by the hedonic calculus. Utilitarianism challenged traditional views that abortion was an 'evil' act, arguing instead that the end justifies the means. Utilitarianism generally supports a pro-choice position, and Mill strongly believed in individual sovereignty:
Natural Law
Natural Law asks what our design or purpose is as humans. One of the primary precepts is to protect and preserve the innocent. This alone leads to a secondary precept 'Do not abort.'
Secondary precepts are absolute deontological principles - there are no exceptions. Many Catholics say that this takes the pressure off people faced with difficult decisions, such as a woman whose pregnancy is threatening her life. Abortion is not an option. Imagine a different issue. A transplant surgeon needs a dozen organs to save the lives of 12 people. He sees a healthy man who has all of these organs. A utilitarian calculation says the greater good would be served by secretly killing this man and saving the other 12 people with his organs. Natural Law says that killing an innocent person is not an option, so you don't have to even consider it.
Situation Ethics
Situation Ethics grew out of a tradition that viewed abortion as an evil act. Fletcher said we should not get rid of rules - they are a useful guide in most situations. However, the only thing good in itself is love, and we may be required to 'push our principles aside and do the right thing'. The Church of England's position, that abortion is evil but may be the 'lesser of two evils' is consistent with a situationist approach. If a woman has been raped, abortion may be an act of love.
Situation ethics say you should act in the 'best interests' of