This morning prior to Mass, my adult acolyte told me he had read the Gospel for Mass and explained to me that John the Baptist was freed from original sin when our Blessed Mother, with Jesus in her womb, visited St. Elizabeth.
This doesn't mean that St. John the Baptist was conceived without original sin, simply born without it by virtue of our Blessed Mother presenting Jesus in her womb to both Elizabeth and Saint John the Baptist in her womb.
There is also a tradition that John the Baptist remained sinless throughout his life.
Thus we celebrate the Nativity of St. John the Baptist. There are only two other nativities the Church celebrates liturgically, our Lord of course, and our Blessed Mother.
Is this new to anyone?
Here is EWTN's take on this in a question and answer form: