I believe and always will that the life of the mother and the child both matter. If BOTH can be survive and live that would be great and a something we should support.
You're completely ignoring quality of life.
If the life of the mother matters, she shouldn't be forced to go through a pregnancy and birth when she doesn't want the child IMO. It's sometimes plain sailing with life carrying on largely as normal and other times both the pregnancy and birth are a physical and mental trauma to the mother.
Birth injuries can affect a woman's life forever, in some cases. Relationships both romantic and familial can be permanently affected by the process of pregnancy and birth. Perhaps a partner doesn't hang around to see how things go or can't cope with supporting someone who isn't having his baby. Perhaps parents aren't great and no longer want someone not working and contributing in their home. Not all jobs can be done whilst pregnant and not many employers will employ a woman who is already pregnant at interview. She may have been in a new job already and they didn't hold the position open for her to return after maternity leave, perhaps it was a hard-won position and her dream career, now lost because she had no option to abort. Or a child who has a terrible pregnancy that means she's unable to continue her studies, stunting her education and affecting her employment prospects, losing her friendships as well perhaps.
So many possibilities and not all of them good. So IMO it's not enough that the mother is alive after birth, she deserves quality of life. Pregnancy and birth is not just some blip that a mother's mind/body and life is guaranteed to recover fully from.
If the life of the child matters, then surely it also matters if the child has a long and miserable life. Or even a short and miserable one. Whether that's due to a medical condition known about before birth, gained during a difficult birth, or just someone unfortunate enough to have a shit life.
Adoption of an unwanted child isn't necessarily some miracle of a happy ending. For one thing, lots of children aren't adopted. Growing up in care isn't a bed of roses.
Worse still for a disabled child/adult, perhaps one who lives in residential care with staff attempting, not always successfully, to manage the person's physical or emotional pain. Or someone disabled enough to need help and to struggle getting help, not disabled enough to very obviously qualify for help, who suffers through their childhood or adult life without the help they need. Their lives matter too. Being alive without quality of life, is awful. I'm not saying disabled people shouldn't exist. Just that it's one thing for parents to choose to birth a child knowing it has a medical condition and choosing to continue with the pregnancy and ongoing care of the child, even if that eventually means a residential care setting. It's quite another thing if a child such as this were to end up in care at birth because a mother who wanted to abort, couldn't. A whole lot of preventable suffering occurring, for a child nobody wanted.
There's been talk recently of how adopted children sometimes "revert to type" genetically and follow in their disastrous biological parents footsteps, in some cases despite not even knowing they're adopted and never having met their birth parents. Damaging not only their own life but the lives of those in the family who raised them, the birth parents who may not have wanted to ever be tracked down but somehow were, and in the case of criminal behaviour the lives of the victims of their crimes. All those people's lives matter too.
Your attitude of "they're born alive and mother survived too - fantastic!" is way too simplistic and discounts all the possible situations of life that any one person could go through.
It's also quite shitty that your response to someone who shared that she had suicidal feelings at the thought of being pregnant by her abusive boyfriend was essentially "sorry, not sorry". I mean, you could have kept your thoughts to yourself and made a general post about your points that was not aimed at that poster. But you didn't.