Barnabas (AD 100 - 1st-2nd century)
The way of light, then, is as follows. If any one desires to travel to the appointed place, he must be zealous in his works...Thou shalt not take the name of the Lord in vain. Thou shalt love thy neighbour more than thine own soul.Thou shalt not slay the child by procuring abortion; nor, again, shalt thou destroy it after it is born.
(Chap 19, The Way of Light) Commenting on the way of Christian conduct. The practice of abandoning a child to die was common among the Roman-Greco culture, particularly if the child was the wrong gender or was suspected to be frail or sick.
Athenagoras (AD 177 - 2nd century)
And when we say that those women who use drugs to bring on abortion commit murder, and will have to give an account to God for the abortion, on what principle should we commit murder? For it does not belong to the same person to regard the very foetus in the womb as a created being, and therefore an object of God’s care, and when it has passed into life, to kill it; and not to expose an infant, because those who expose them are chargeable with child-murder, and on the other hand, when it has been reared to destroy it.
(Chapter 35, The Christians Condemn and Contest All Cruelty) Commenting on the charge that Christians are cannibals and support murder for some people.
Tertullian (AD 145 - 2nd century)
Now the entire process of sowing, forming, and completing the human embryo in the womb is no doubt regulated by some power, which ministers herein to the will of God, whatever may be the method which it is appointed to employ. Even the superstition of Rome, by carefully attending to these points, imagined the goddess Alemona to nourish the foetus in the womb; as well as (the goddesses) Nona and Decima, called after the most critical months of gestation; and Partula, to manage and direct parturition; and Lucina, to bring the child to the birth and light of day. We, on our part, believe the angels to officiate herein for God.The embryo therefore becomes a human being in the womb from the moment that its form is completed. The law of Moses, indeed, punishes with due penalties the man who shall cause abortion, inasmuch as there exists already the rudiment of a human being, which has imputed to it even now the condition of life and death, since it is already liable to the issues of both, although, by living still in the mother, it for the most part shares its own state with the mother.
(Chapter 37, On the Formation and State of the Embryo) Terutullian is giving a defense of the human soul and its relation to God. There were certain sects of false teachings that stated that a soul did not come into being until after its birth. Tertullian's apology expands several chapters on this subject (more than 53 chapters).
Felix - The Octavius (AD 210 - 3rd century)
“And now I should wish to meet him who says or believes that we are initiated by the slaughter and blood of an infant. Think you that it can be possible for so tender, so little a body to receive those fatal wounds; for any one to shed, pour forth, and drain that new blood of a youngling, and of a man scarcely come into existence? No one can believe this, except one who can dare to do it. And I see that you at one time expose your begotten children to wild beasts and to birds; at another, that you crush them when strangled with a miserable kind of death. There are some women who, by drinking medical preparations, extinguish the source of the future man in their very bowels, and thus commit a parricide before they bring forth...To us it is not lawful either to see or to hear of homicide; and so much do we shrink from human blood, that we do not use the blood even of eatable animals in our food.
(Chapter 30, The Story About Christians Drinking the Blood of an Infant That They Have Murdered, Is a Barefaced Calumny. But the Gentiles, Both Cruelly Expose Their Children Newly Born, and Before They Are Born Destroy Them by a Cruel Abortion. Christians Are Neither Allowed to See nor to Hear of Manslaughter. Felix is refuting several lies told about Christians and demonstrating why they are not true.