This has long been a favored argument of the abortionists.
It comes entirely from a single verse in the Bible, Genesis 2:7 when God breathes the Breath of Life into Adam's face and Adam becomes a living soul.
However, the abortionists overlook one very important fact and that is that Adam was CREATED EX NIHILO and God breathing the Breath of Life is a SINGULAR EVENT. God DOES NOT do this for anyone else, Adam's humanity passed to Eve WITHOUT God breathing in her face and it has subsequently passed to all of us without this as well.
Jer 1:5 Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, [and] I ordained thee a prophet unto the nations.