Nativity of the Mother of God (Theotokos) (September 8)
The Church does not customarily celebrate the earthly birthdays of the Saints, but rather their heavenly birthday, their date of death which, for them, is the start of their eternal life. The Church observes the earthly birthdays of only two Saints, the Most Pure Virgin Mary and St. John the Baptist.
The feast of the Nativity of the Mother of God is an ancient feast which was first observed in Syria and Palestine as early as the 5th or 6th century. It was officially introduced in the Eastern Church by the Emperor Mauricius (Mauritius) at the beginning of the 7th century. The traditional feast day of September 8 may have been selected because it falls exactly nine months after the feast of the Immaculate Conception of Mary on December 8.
The Gospels record very little information about the life of the Mother of God. The source for the birth story of the blessed Virgin Mary may be the apocryphal Protoevangelium of James, written about 150 A.D. From this work we learn about Mary's parents Joachim and Anna and the events of her birth.