Mary was conceived without sin, and chosen at the beginning of time to be the Mother of Christ. Her sin was forgiven, thus, before she was born.
God can do all things. It’s called the Immaculate Conception.
Do some studying on it and you will find out that this is the truth.
Study of God’s word tells me nothing of the immaculate conception doctrine. Quite the opposite.
Catholics peddle myths and fables. They do not hold up the word of God as authoritative. No thanks.