where in the bible did it say we should pray for our children and the unborn?

Answer 1

It doesn't say to pray but to teach the decrees of God

Psalm 78

5 He decreed statutes for Jacob
and established the law in Israel,
which he commanded our forefathers
to teach their children,

6 so the next generation would know them,
EVEN THE CHILDREN YET TO BE BORN,
and they in turn would tell their children.

There is a passage where Samson's father asks the angel of the Lord how to prayer for Samson even before the boy is to be born

Judges 13:8
Then Manoah prayed to the LORD : "O LORD, I beg you, let the man of God you sent to us come again to teach us how to bring up the boy who is to be born."

God bless you exceeding abundantly and be fruitful

Answer 2

we should pray for everyone