About abortion.?

Let us say I have a vehicle accident and am let paralyzed. I still love life, am able to eat, drink, watch movies read books, enjoy sunsets but cannot move without help. In case a friend brings me out of the house in my wheel chair, it not my situation outside the house quite similar to what it was when I was inside the house? That being said is the situation of unborn babies seems  just about the same thing? I hear of 6 month old babies who are born early and live quite a healthy life. So why is there a law that allows babies to be killed after 6 months just for the convenience of the mother (even though the mother has the option to allow it to live then put it up for adoption) So it seems very obvious that it is just a question of convenience. So, in case one follows this path of logic, might not one of the next step be to terminate the lives of the physically or mentally challenged people just because they might be an inconvenience. (like they did in Nazi Germany a bit before the start of WW2. So my question is Are we not , in the not to distant future in danger of implementing such a law?.