For those who say that the Catholic Church has not maintained a constant witness against abortion from the beginning, the link gives the rich detail. Here are two teachings from the first century, in the age of the Apostles. The rest in the link.
The Didache
“The second commandment of the teaching: You shall not murder. You shall not commit adultery. You shall not seduce boys. You shall not commit fornication. You shall not steal. You shall not practice magic. You shall not use potions. You shall not procure [an] abortion, nor destroy a newborn child” (Didache 2:1–2 [A.D. 70]).
The Letter of Barnabas
“The way of light, then, is as follows. If anyone desires to travel to the appointed place, he must be zealous in his works. The knowledge, therefore, which is given to us for the purpose of walking in this way, is the following. . . . Thou shalt not slay the child by procuring abortion; nor, again, shalt thou destroy it after it is born” (Letter of Barnabas 19 [A.D. 74]).
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