Sacred Scripture is the account of God's special relationship with humanity in the course of salvation history. One way the sacred writers would call attention to this unique relationship between God inhumanity was by emphasizing the special births of important religious persons to women recognized as long past that the years of childbearing. In this way, what was he humanly impossible with scene is possible only through the presence, activity and providence of God.
Two examples immediately come to mind. One is the birth of Isaac by Sarah when she and Abraham were in their old age long after she was capable of bearing children. The other example is the birth of the Forerunner, St. John the Baptist, to Zechariah and Elizabeth after she too had been ridiculed by her peers for being unable to bear children.
Today the Church in her Sacred Tradition gives witness to God's special involvement with us in the importance of the Mother of God in salvation history by first emphasizing the barrenness of St. and and therefore celebrating her conception of Mary.
For the Church, Mary always held a unique and venerated role. She is seen as the New Eve, the mother of a restored in revived humanity. Her stature has both the Mother of God and Mother of the Church gives witness that God is not removed from humanity. On the contrary, God is with us in Christ.
As we celebrate the conception of Mary in the barren womb of St. Anne, we are asked to read and reflect on Jacob's dream of the ladder bridging earth and heaven. (Genesis 28:10-17) this dream becomes a reality in the conception and person of the Mother of God. God descends to interact with a human couple (Joachim and Anna) in their sterility. Humanity in turn conceives and gives birth to a sinless woman who, in giving birth to Jesus the Son of God, will help it ascend and encounter God the Father. In Christ, through Mary, we stand assured that God is not isolated from us. Rather God is always with us, and we are as in Him.