[TheFourthMagi]

The earliest source is an anonymous church manual of the late first century called The Didache. It commands “thou shall not murder a child by abortion nor kill that which is begotten.” (at 2.2)

It isn't anonymous. The primary authors of the original core of the Didache were Paul and Barnabus. They wrote it in the 40's A.D. and it is a version of the sample sermon that wound up securing the historic agreement noted in Acts 15.

[wagglebee]

I believe it was added to after the deaths of Saints Paul and Barnabas.