The LORD devotes a whole chapter in Psalms to help us understand the reality of a life yet unborn.
Proverbs 139 stands as a pillar in the faith of a believer that even before birth each person is known to GOD.
"I will praise thee; for I am fearfully and wonderfully made: marvellous are thy works; and that my soul knoweth right well.
"My substance was not hid from thee, when I was made in secret, and curiously wrought in the lowest parts of the earth.
Thine eyes did see my substance, yet being unperfect; and in thy book all my members were written, which in continuance were fashioned, when as yet there was none of them.
How precious also are thy thoughts unto me, O God! how great is the sum of them!"
Psalms 139:14-17