This is a difficult topic. Some biblical references would help to understand how God views an unborn child:
God views the life of a child as precious even during the very early stages of development after conception:
For 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.
God stated that a person would be called to account for injury to an unborn child:
If people are fighting and hit a pregnant woman and she gives birth
prematurely[a] but there is no serious injury, the offender must be
fined whatever the woman’s husband demands and the court allows.
It's a very serious sin to willfully take a human life for any reason not authorized by God:
Whoever sheds human blood, by humans shall their blood be shed; for
in the image of God has God made mankind.
“You must not murder.”
So the life of a child is very valuable in God's eyes. If a medical decision must be taken between mother's or child's life, this is up to the couple. If the doctors inform the parents that the child will be born with medical problems, this is no reason to murder the child.