Campion, bless you.
You are the first person —in many years-—who I have heard refer to “pharmakeia”. Yes, it was not only an ancient contraceptive potion, but also acted as an abortifacient.
At this moment, I can’t recall where it occurs in the Epistles of Paul, but he does make a negative referral to pharmakeia.
You are right:every Christian group did reject contraception until the Lambeth Conference took place in 1930.
useful graphic at: http://thomasgwyndunbar.wordpress.com/2010/06/09/conception-to-implantation-timeline/