The term 'post-birth abortion' is misleading at best - what this is essentially asking is whether parents should be able to euthanase babies after they've been born.
And I don't think so. Terminally ill adults probably should, with counselling and proper medical advice, be able to end their own life. Parents also have to make some tough decisions with the health of the children - for example they may be asked to make a decision about life support. But overwhelmingly, the ability to euthanase a baby that has already been born based on the baby being 'undesirable' is crazy - if the parents can't/won't look after the child, they can put it up for adoption.