I'll let
JLB answer this, but would also like to give you my perspective on this.
God does not select before the womb who will spend eternity with Him or those who will spend eternity in the lake of fire. God is a sovereign God that in his love and patience for us would not want anyone to perish and only God knows the intents of the heart as he alone judges us, 2 Peter 3:9. God wants all of us to come to repentance, but not everyone will for the way they are raised from birth. Many babies are born into families that have rejected God and will be raised to also come against Him as their hearts are hardened.
Age of accountability is nowhere found in the Bible and is a preconception that only leads to speculation. Infant baptism is also unscriptural as a baby can not know faith and regeneration as this takes place at the same point in time. A baby can not be covered by the blood of Jesus until they come into the knowledge of good and evil and accept Him as Lord and Savior. Many use Ephesians 1:4, 5 to support this, but that is not what these verses are saying. These two verses are very similar to that of 2 Peter 3:9 that through Gods love he breathed his breath (spirit) into us when we first came from the womb making us a living soul and that he would want us to be holy and without blame. Staying holy without blame is through repentance and acceptance that brings us to that adoption that is in Christ Jesus thus we were made for Gods good pleasure.
Ephesians 1:4 According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love: 5 Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will,
Zechariah 12:1 The burden of the word of the LORD for Israel, saith the LORD, which stretcheth forth the heavens, and layeth the foundation of the earth, and formeth the spirit of man within him.
A baby can not inherit the sin of the parents, but are born with a sin nature. Adams sin was imputed to every one of us as there is none that are righteous, babies included, Romans 5:12-18. Psalms 58:3 says, The wicked are estranged (turn from God) from the womb: they go astray as soon as they be born, speaking lies. Who taught a child to lie or be rebellious against their parents? It's that sin nature that causes a child to do this. Psalms 51:5 says, Behold, I was shapen in iniquity; and in sin did my mother conceive me. The only thing God gave us at birth was His very breath (spirit) that made us a living soul and it's that breath that goes back to God when we die as he preserves it in judgment until the coming of the Lord, Ecclesiastes 12:7.
Rom 9:11 (For the children being not yet born, neither having done any good or evil, that the purpose of God according to election might stand, not of works, but of him that calleth;)
In the OT and NT God did specifically call out certain prophets by name (listed below) as he elected them before they were even formed in the womb. This does not make God a respecter of person, it just means they were called