The driving force behind the anti-abortion movement is the Catholic Church

[Klaralven]

30. Respect for Unborn Human Life: The Church's Constant Teaching

Fact sheet by the United States Conference of Catholic Bishops Committee on Pro-Life Activities

The Catechism of the Catholic Church states: "Since the first century the Church has affirmed the moral evil of every procured abortion. This teaching has not changed and remains unchangeable. Direct abortion, that is to say, abortion willed either as an end or a means, is gravely contrary to the moral law" (No. 2271).

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In 1827, with the discovery of the human ovum, the mistaken biology of Aristotle was discredited. Scientists increasingly understood that the union of sperm and egg at conception produces a new living being that is distinct from both mother and father. Modern genetics demonstrated that this individual is, at the outset, distinctively human, with the inherent and active potential to mature into a human fetus, infant, child and adult. From 1869 onward the obsolete distinction between the "ensouled" and "unensouled" fetus was permanently removed from canon law on abortion.

Secular laws against abortion were being reformed at the same time and in the same way, based on secular medical experts' realization that "no other doctrine appears to be consonant with reason or physiology but that which admits the embryo to possess vitality from the very moment of conception" (American Medical Association, Report on Criminal Abortion, 1871).

Thus modern science has not changed the Church's constant teaching against abortion, but has underscored how important and reasonable it is, by confirming that the life of each individual of the human species begins with the earliest embryo.

Given the scientific fact that a human life begins at conception, the only moral norm needed to understand the Church's opposition to abortion is the principle that each and every human life has inherent dignity, and thus must be treated with the respect due to a human person. This is the foundation for the Church's social doctrine, including its teachings on war, the use of capital punishment, euthanasia, health care, poverty and immigration. Conversely, to claim that some live human beings do not deserve respect or should not be treated as "persons" (based on changeable factors such as age, condition, location, or lack of mental or physical abilities) is to deny the very idea of inherent human rights. Such a claim undermines respect for the lives of many vulnerable people before and after birth.

https://www.usccb.org/issues-and-action/human-life-and-dignity/abortion/respect-for-unborn-human-life