noun which may take the genitive case particle 'no', noun, adverb
before one's birth; before one was born
Literary or philosophical expression, often used in Buddhist or poetic contexts to refer to the time before one's existence. Can function as a noun, no-adjective, or adverb.
It is difficult to think about oneself before birth.
He tried to imagine the world before he was born.
生前 refers to the time when one was alive (before death), while 未生以前 specifically means before one's birth.
Compound of 未生 (みしょう, 'unborn') and 以前 (いぜん, 'before'). The term is associated with Buddhist philosophy, referring to the state prior to birth.