My reflection is from The Little Blue Book:
“Today’s feast of the Immaculate Conception of the Blessed Virgin Mary is often mistakenly thought to refer to the way Mary conceived Jesus in her womb.
’Immaculate Conception’ actually means Mary received immediately from God what people receive at baptism. From her conception, she was free from sin – immaculate. 
A feast of the Conception of Mary was celebrated in both the Eastern and Western churches for many centuries. After Pope Pius IX  solemnly defined the doctrine of the Immaculate Conception on December 8, 1854, this feast was officially designated as the ‘Immaculate Conception of the Blessed Virgin Mary and the date for its celebration was fixed as December 8.”
Hail, Mary, full of grace. 
