Since we are in the Christianity sub- forum I feel pretty ok with saying that all life is precious and given by God Almighty. He breathes life into His creation. When the sperm fertilizes the egg a complete separate and unique life apart from the parents begins to grow.

Jeremiah 1:5 Before I formed you in the womb I knew you, and before you were born I set you apart and appointed you as a prophet to the nations.”

This clearly states the the creator knew His creation before conception that is a plan and a purpose.

Psalm 139:13For you created my inmost being;
you knit me together in my mother’s womb.
14 I praise you because I am fearfully and wonderfully made;
your works are wonderful,
I know that full well.
15 My frame was not hidden from you
when I was made in the secret place,
when I was woven together in the depths of the earth.
16 Your eyes saw my unformed body;
all the days ordained for me were written in your book
before one of them came to be.
17 How precious to me are your thoughts,[a] God!
How vast is the sum of them!
18 Were I to count them,
they would outnumber the grains of sand—
when I awake, I am still with you.

This is a creator that lovingly designed and created us and knew us beforehand

Luke 1:15 for he will be great in the sight of the Lord. He shall never take wine or strong drink, and he will be filled with the Holy Spirit even from his mother’s womb.

This says the John the Baptist was filled with the Holy Spirit of God even in the womb. While he was in the womb he leapt for joy when Mary who was pregnant with Jesus spoke.

To limit a pre born child to a non person is pretty sad. Abortion makes me sad. It's cold and heartless. I wonder if the next step is the same acceptance of euthanizing our disabled and elderly.
Without taking sides ... it seems to me that the initial bundle of cells is destined to become a human being, unless something natural or unnatural interrupts the process – and in that sense it is a human being, it's not a dog or bird of leaf ... so intentionality plays a part here.

A like discussion could be at what point a person with impaired faculties ceases to be a human being? A very difficult moral question, as we get into eugenics and all manner of issues.