The Catholic church has taught against abortion from the very earliest days! I have listed only a very few of the earliest ones here. Not only do they state that life begins at conception but that any abortion at any time is murder.
The Teaching of the Twelve Apostles: The Didache (1st Century AD)
The Lord’s Teaching to the Heathen by the Twelve Apostles:
Now, this is the way of life:…
The second commandment of the Teaching: “Do not murder; do not commit adultery”; do not corrupt boys; do not fornicate; “do not steal”; do not practice magic; do not go in for sorcery; do not murder a child by abortion or kill a newborn infant…
The Apocalypse of Peter (ca. 135)
“I saw a gorge in which the discharge and excrement of the tortured ran down and became like a lake. There sat women, and the discharge came up to their throats; and opposite them sat many children, who were born prematurely, weeping. And from them went forth rays of fire and smote the women on the eyes. These were those who produced children outside of marriage and who procured abortions.” 2:26
“Those who slew the unborn children will be tortured forever, for God wills it to so.” 2:64
Tertullian (c. 160 - 240)
It is not permissible for us to destroy the seed by means of illicit manslaughter once it has been conceived in the womb, so long as blood remains in the person. - Apologia, cap 25, line 42
Now we allow that life begins with conception because we contend that the soul also begins from conception; life taking its commencement at the same moment and place that the soul does" , - De Anima 25, line 27
Basil (c. 329-379)
To Anfilochius, Bishop of Iconia:
She who has intentionally destroyed [the fetus] is subject to the penalty corresponding to a homicide. For us, there is no scrutinizing between the formed and unformed [fetus]; here truly justice is made not only for the unborn but also with reference to the person who is attentive only to himself/herself since so many women generally die for this very reason.
-First Letter 2
You may see many women widows before wedded, who try to conceal their miserable fall by a lying garb. Unless they are betrayed by swelling wombs or by the crying of their infants, they walk abroad with tripping feet and heads in the air. Some go so far as to take potions, that they may insure barrenness, and thus murder human beings almost before their conception. Some, when they find themselves with child through their sin, use drugs to procure abortion, and when (as often happens) they die with their offspring, they enter the lower world laden with the guilt not only of adultery against Christ but also of suicide and child murder. - Epistula 22
The Apostolic Constitutions
Thou shalt not use magic. Thou shalt not use witchcraft; for he says, ‘You shall not suffer a witch to live’ [Ex. 22:18]. Thou shall not slay thy child by causing abortion, nor kill that which is begotten. . . . *f it be slain, [it] shall be avenged, as being unjustly destroyed" (Apostolic Constitutions 7:3 [A.D. 400] ).