With the dogma of the Immaculate Conception, the Catholic Church affirms that Mary, on account of a singular privilege bestowed by God and in view of the merits of Christ's death, was preserved from contracting the stain of original sin and came into existence already completely holy. Four years after being defined by Pope Pius IX, this truth was confirmed by the Madonna herself at Lourdes in an apparition to Bernadette with the words: "I am the Immaculate Conception."
Fortunately there was emperical evidence to back up that immaculate conception tale otherwise there might be some skeptics around who would feel that this was some fiction cooked up by some Pope and not something that actually happened in the real world, and so it is good that we have the rock solid word of Bernadette.
I find it interesting to note that apparently being born very sinful is an arbitrary thing, for it would seem that the only reason why anyone has sin is because God is like a manufacturer who produces nothing but defective toasters. Now we know that it is possible for God to manufacture a half decent toaster once in a while, should the mood come upon God to create a human being without a sin so that like Mary, God's wife, people could be born into the world saved rather than being born damned thus making a lot of work for priests who must exhaust themselves trying to rectify God's mistakes. It turns out that only Mary, the mother of God, could get in on that deal of being arbitrarily born without any sin, since apparently that isn't a requirement and being born sinful and damned is just something that God does on purpose simply because God is God and therefore there isn't a damn thing anyone can do about it. So there.
For Mary it would be birth without a sin and for everyone else it would be sacraments and penance and lots and lots of religion, since keeping a priest busy was apparently all part of the divine plan of God. Either that or this must be some kind of make work project cooked up by priests, because, after all, who wants to be out of a job?