Ancient Christians in many places followed tradition from the book of Enoch which attests to doctrines like the Trinity, the prayers of saints etc. Enoch also directly attests to life in the womb and that it was a fallen Angel that taught the procedure of abortion.
From chapter 69
Chapter 69]
1 And after this judgement they shall terrify and make them to tremble because they have shown this to those who dwell on the earth. 2 And behold
further on:
And the fifth was named Kasdeja: this is he who showed the children of men all the wicked smitings of spirits and demons, and the smitings of the embryo in the womb, that it may pass away, and [the smitings of the soul]
The Book of Enoch, Section II
An ancient church manual ( the Didache) from about 100 AD specifically uses the term abortion as a form of murder.
Chapter 2. The Second Commandment: Grave Sin Forbidden. And the second commandment of the Teaching; You shall not commit murder, you…….
you shall not murder a child by abortion nor kill that which is born. You
Didache. The Teaching of the Twelve Apostles (translation Roberts-Donaldson).
While these are totally valid evidence that Christianity is pro life and opposed to abortion, I cannot fully say that this positively includes life at conception. I tend to believe that these do support life at conception.
I do not mean to include this for any political commentary but just for perspective on faith tradition. Enoch is an interesting writing in that it seems interwoven among small areas of the New Testament. St. Jude quoted a small portion in his brief epistle, it has connections to the book of Revelation, & even Daniel in the Old Testament.