Jesus was exactly the sort of child who would have been aborted. By law and custom both, Mary's pregnancy ought to have come to an untimely and violent end.
Unlike the Koran, the Old Testament makes no allowance for protecting the unborn when it calls for the execution of adulteresses. Had Joseph acted according to the letter of the law, Christ would have died before taking his first breath on earth.
But I do know that the gospels tell us that Joseph was a righteous man, and his righteousness was manifested in mercy. Even before the angel appeared to him in the night, where the law prescribed death, Joseph chose life for the Holy Child and His mother.
It is because of Jesus that I can still trust in the goodness of God, and the mercy of Jesus inexorably leads me to care about the unborn.
Because of Jesus, I am pro-mercy, pro-redemption, pro-the-least-of-these, pro-woman. And because of all that, I am pro-life.
The law hands out death to the born and the unborn both; it is grace that saves us all. There is no biblical way to be pro-life except by way of the lavish and undeserved mercy of Jesus Christ. There are no short-cuts.
I am pro-life by the very grace through which I live.