Here are transcripts from a sermon by John MacArthur:
Children and the Kingdom of God, Part 1
Children and the Kingdom of God, Part 2

What I mean by that is when an infant dies, or a child dies before reaching the condition of accountability, I think Scripture gives us enough insight to be sure that they are saved, they are gathered together by God into His presence, just as God in Isaiah 40 gathers the little lambs and carries them. I think God has a special affection for them and when they die He gathers them into His presence. And I want to show you how I think the Scripture lays that out for us.

Luke 18:15-17