Immaculate Conception
Another misunderstanding is that, by her immaculate conception, Mary did not need a saviour. When defining the dogma in Ineffabilis Deus, Pope Pius IX explicitly affirmed that Mary was redeemed in a manner more sublime. He stated that Mary, rather than being cleansed after sin, was completely prevented from contracting Original Sin in view of the foreseen merits of Jesus Christ, the Savior of the human race. In Luke 1:47, Mary proclaims: "My spirit has rejoiced in God my Saviour." This is referred to as Mary's pre-redemption by Christ. Since the Second Council of Orange against semi-pelagianism, the Catholic Church has taught that even had man never sinned in the Garden of Eden and was sinless, he would still require God's grace to remain sinless.

Q: What was explained by the man  Giovanni Maria Mastai-Ferretti who later became leader of the Holy Roman Church ?
dogma in Ineffabilis Deus, Pope Pius IX explicitly affirmed that Mary was redeemed in a manner more sublime