There's no doubt that everyone is exhorted to pray throughout the Bible. The nine days is traditional. Somehow, the people picked up the habit of praying for specifically "nine" days for certain intentions. They probably picked up the idea from their pagan neighbors. (Don't freak, praying is good.) Also, nine is recognized as the time for a baby gestation. And if you want a Bible reference: it is believed that the time between Jesus' Ascension and Pentecost was nine days. And in Acts we see the disciples gathered together in prayer (Acts 1: 12-14)
So if the disciples prayed from the Ascension to Pentecost, they invented the first novena. The people--lay people continued praying throughout our centuries for nine periods. It wasn't a church initiative. Finally, sometime in the nineteenth century, a pope proclaimed that novenas were acceptable and even admirable.
Well, you know how it is. As I read the comments on the site, a commenter happened to write about his favorite novena to Our Lady of Confidence. So I spent more time googling Our Lady of Confidence. This is from Spirit Daily.
As a little prayer card explains, "Our Lady of Confidence has a long record of granting many remarkable favors through the veneration of her under this title. She has been revered in Italy in many churches, but the most notable shrine in her honor under this title is the Chapel of the Major Seminary in the Lateran Palace in Rome.
"Pope John XXII, an alumnus of this seminary, often prayed before the picture of Our Lady of Confidence in this chapel and celebrated his first Mass there and as the Holy Father he was still a frequent visitor.
"Twice in past centuries, the city of Rome was saved from the ravages of cholera after the people prayed to Our Lady of Confidence. During World War One, the superiors and students of the Roman Seminary placed under her protection the 124 seminarians who were called to serve in the armed forces. All of them returned safely to the seminary.
"In 1941, a Dominican sister in Michigan made a remarkable recovery after the sisters at her bedside invoked the help of the Blessed Lady with the aspiration, 'My Mother, My Confidence."
This devotion has ecclesiastical approval:
"O Mary Immaculate, the precious name of Mother of Confidence, with which we honor you, fill our hearts to overflowing with the sweetest consolation and move us to hope for every blessing from you. If such a title has been given to you, it is a sure sign that no one has recourse to you in vain. Accept, therefore, with a mother's love, our devout homage, as we earnestly beseech you to be gracious to us in our every need. We pray that you will make us live in constant union with you and your Divine Son Jesus. With you as our guide, we are certain that we shall walk in the right way and that it will be our happy lot to hear you say on the last days of our lives those words of comfort: 'Come, my good and faithful servant, enter into the joy of the Lord."