God already had Jeremiah in mind before he was born. At that time, he was already occupied with Jeremiah. Jeremiah 1:5 uses different verbs to indicate this: formed, knew, consecrated, and appointed (as prophet). Before his birth, God had set him apart for a special task: to be God’s prophet to all nations.
5 Avant que je t'aie formé dans le ventre de ta mère, je te connaissais, et avant que tu sois sorti de son sein, je t'avais consacré, je t'avais établi prophète des nations.