The Immaculate Conception Doctrine attempts to explain how a sinful woman could bear a sinless child, but fails miserably in the face of the clear evidence that Mary realized she was in need of a Savior. From The Message Bible:
Luke 1:46 -55 And Mary said,
I'm bursting with God-news;
I'm dancing the song of my Savior God. God took one good look at me, and look what happened—
I'm the most fortunate woman on earth!
What God has done for me will never be forgotten,
the God whose very name is holy, set apart from all others.
His mercy flows in wave after wave
on those who are in awe before him.
He bared his arm and showed his strength,
scattered the bluffing braggarts.
He knocked tyrants off their high horses,
pulled victims out of the mud.
The starving poor sat down to a banquet;
the callous rich were left out in the cold.
He embraced his chosen child, Israel;
he remembered and piled on the mercies, piled them high.
It's exactly what he promised,
beginning with Abraham and right up to now.