In Catholic morality, abortion is either direct (induced) or indirect. Direct abortion is any destruction of the product of human conception, whether before or after implantation in the womb. A direct abortion is one that is intended either as an end in itself or as a means to an end. As a willful attack on unborn human life, no matter what the motive, direct abortion is always a grave objective evil.
Indirect abortion is the foreseen but merely permitted evacuation of a fetus which cannot survive outside the womb. The evacuation is not the intended or directly willed result, but the side effect, of some legitimate procedure. As such it is morally allowable.
The essential sinfulness of direct abortion consists in the homicidal intent to kill innocent life. This factor places the controverted question as to precisely when human life begins, outside the ambit of the moral issue; as it also makes the now commonly held Catholic position that human life begins at conception equally outside the heart of the church's teaching about the grave sinfulness of direct abortion.
Abortion has been condemned by the Church since apostolic times. The Teaching of the Twelve Apostles, composed before A.D. 100, told the faithful "You shall not procure abortion. You shall not destroy a newborn child" (II, 2). Direct abortion and infanticide were from the beginning placed on the same level of malice.
Hundreds of ecclesiastical documents from the first century through to the present testify to the same moral doctrine, with such nuances as time, place, and circumstances indicated. The Second Vatican Council declared: "Life must be protected with the utmost care from the moment of conception," so that "abortion and infanticide are abominable crimes" (Constitution on the Church in the Modern World, IV, 51). Pope Paul VI confirmed this teaching in 1974. "Respect for human life,' he wrote, "is called for from the time that the process of generation begins. From the time that the ovum is fertilized, a life is begun which is neither that of the father nor of the mother. It is rather the life of a new human being with its own growth. It would never be made human if it were not human already." Consequently, "divine law and natural reason exclude all right to the direct killing of an innocent human being" (Declaration on Procured Abortion, III, 12). (Etym. Latin abortivus, born prematurely, abortive; from aboriri, to miscarry.)