Clearly there is no historical record of the birth of Mary. The Church does believe, however, that from the very moment of her conception she was totally free from sin and remained free of sin for her whole life. It was not acceptable that Jesus, the Son of God, should be conceived in a body tainted by sin. Her birth, then, is clearly something to celebrate. The Church, too, has given names to her parents – Joachim and Ann, whose feast is celebrated on 26 July.
The Churches both in the East in Constantinople and in the West in Rome have been celebrating Mary’s birth since the 6th and 7th centuries.
The liturgy traces its origins to the consecration of a church in Jerusalem, known as St Ann’s Basilica, in the 6th century. Before that there had been a 5th century basilica in honour of Mary on a site known as the “Shepherd’s Field” and supposedly the home of Joachim and Ann. It was replaced by a new basilica in the 6th century which was consecrated to St Ann.
Monks from the East brought the feast to Rome in the 7th century. From there it spread through the western Church. By the 13th century it had been raised to a solemnity with a major octave and a vigil which was a fast day. Pope Sergius I (687-701) instituted a procession from the Roman Forum to the basilica of St. Mary Major for the feast.
Following the liturgical reforms of Pope St Pius X, the feast had just a simple octave for the feast and in 1955 Pope Pius XII abolished the octave altogether. The liturgy now has the rank of feast.
The date, September 8, was chosen as the octave day of the former Byzantine New Year. Although the feast was celebrated on various dates over the centuries, September 8 predominated. The feast celebrating Mary’s conception without sin on December 8, was later set to correspond to nine months preceding Mary’s birth (just as the Annunciation precedes the Birth of Jesus by nine months).
In the Eastern Church, Mary’s birthday is celebrated as one of the twelve great liturgies. The title for the liturgy in the East is: “The Birth of Our Exalted Queen, the Birthgiver of God and Ever-Virgin Mary”.