The Roman Catholic Church says that deliberately causing an abortion is a grave moral wrong. It bases this doctrine on natural law and on the written word of God.
The Church says that human life begins when the woman's egg is fertilized by a male sperm.
From that moment a unique life begins, independent of the life of the mother and father. The features that distinguish us from our parents - the colour of our eyes, the shape of our face - are all laid down in the genetic code that comes into existence then.
Each new life that begins at this point is not a potential human being but a human being with potential.
Since the sixteenth century, causing or having an abortion led to automatic excommunication.
This is stated in the Code of Canon Law (1983): "A person who actually procures an abortion incurs automatic excommunication" (Canon 1398).
The Church condemned abortion as early as the 2nd century CE: the Didache, written in the 2nd century (some time after 100 CE), states: "You shall not kill the embryo by abortion and shall not cause the newborn to perish."
Early Christian doctrine is clear on the matter.