In my experience people who make this argument are making it from the luxury position of behind a screen, knowing they’ll never have to personally be involved with such a messy business, that ‘other people’ will have it on their conscience instead.
If they were handed the lethal injection and instructed to end the life of a 35 week foetus, I guarantee they would suddenly appreciate the moral dilemma behind late terminations, and understand why it is unethical to expect doctors to carry them out as part of a professional ‘duty’.
Equally they can rarely say when exactly this right ends and the rights of the baby begin. When it’s head is born? When the feet are out? When the cord is cut? When the mother has stopped breastfeeding as technically the baby is still dependent on her body for life until then?
‘As early as possible as late as necessary’ is simply a catchy mantra for those who will never personally be involved in the late termination of a healthy baby. And they know that.