This issue is very difficult for me. On an individual basis, it is very hard for me to say that a particular child should not be saved, but the cost to society for some of these children is enormous, and their quality of life is very poor. The most disturbing part is that this could easily become the thin edge of a potentially very thick wedge; where do you draw the line?
Twelve or 13 years ago, I was working as a paraprofessional (teacher's aide) in a severe needs program. There were two children in the program who had been born prematurely. One was born at 6 1/2 months, was profoundly hard of hearing, had mild cerebral palsy affecting his entire body, and was born with an intestinal disorder that required multiple surgeries. At the age of 7, he had no useful communication skills, was not toilet trained, and would only eat food that had been pureed (due to complications from the surgery, solid food made him sick, so he wouldn't eat it). Over the course of the school year, he learned something between 5 and 10 signs - food, water, toilet, etc. - to begin to be able to communicate his basic needs. This amount of progress took an entire school year. In the meantime, he had tantrums when he couldn't express his needs (often) and often tried to claw or bite people who changed his diaper. I finished my teaching certificate and moved to another school district; I don't know what happened to him after that.
The other was a girl who was born at 5 1/2 months, before her skull formed - which it never did; when her head moved, you could see her brain move under her scalp, unless she was wearing her helmet (most of the time). She had a permanent tracheotomy, and therefore couldn't speak; her fine motor skills were not good enough to even attempt basic signs; we only knew she could hear because she would smile when we said her name. She ate (if you want to call it that) liquid Enfamil through a stomach tube. She was in a wheelchair, and could only move her arms and hands enough to hold a marker in her fist and wave it across a piece of paper; I can't call what she did writing, or even scribbling. Because she needed to be at a school that could meet her needs, her bus ride each way to school was 50 minutes long. One day her tracheotomy clogged, and the bus driver had to pull over and call an ambulance, as neither he nor the bus aide had any training in how to help her. After being taken to the hospital, it was determined that she had pneumonia, which she succumbed to after several months of treatment. She was 10 years old.
There was another girl in the program who had a hereditary genetic disorder that caused toxins to builld up in her brain, reducing her intelligence... whch, due to the disorder, was never high to begin with. She peaked, intellectually, when she learned to eat with a spoon, a skill she had lost by the time I met her. She could stand (in a stander; her balance was quite poor), wore a diaper, had no speech, and was slowly dying. When I knew her she was 11; her life expectancy was somewhere around 15. I finished my teaching certificate and moved to another school district; I don't know what happened to her after that.
More recently, as a teacher, I knew a family that had several children with Huntington's Chorea. When a person has one copy of the gene, causing the adult onset variation, s/he usually dies in his 30s. These children had 2 copies, causing the juvenile onset variant. They were happy, outgoing, communicative children who knew they were dying, and had known it all their lives. All three of them died in high school.
All of these children had illnesses that were diagnosed at birth or shortly thereafter, and would have been affected by this issue. I could go on, but I won't; it depresses me.
Despite their difficulties, all of these were loved by their parents, who did the best they could with the circumstances handed to them. Many of them would not have survived birth or infancy 10 or 20 years before they were born; for the 2 who were premature, the technology that saved their lives also caused, or exacerbated, many of their problems... but for others born in similar circumstances, things have been much better. There is no way to know, for many of them, how much damage there is until they begin to develop... or fail to do so. In the abstract, it is easy to say that these children and others like them are a burden on society, and should not be allowed to live - or at least that their parents should have the option of withholding medical care, along the same lines as a living will for people with terminal illnesses - when one begins to deal with individual children, to know them, the issues are not so clear. Were I to have a child born with severe problems, and the option to not save the child were available, I don't know what I would do. I hope to never find out.