So you are in favor of the right of mothers to have a baby in an alley and leave it to death?
I say death, because that is what will happen most likely, without any assistance from third parties. What if the mother has a baby in the desert or in a rural mountain town in Colorado, where third parties aren't around? Can we leave a baby in the snow to fend for itself because it is a 'physically independent entity' that has a self responsibility to gain 'the values it requires to sustain its own life.'
The baby is physically dependent on the mother because of its undeveloped nature, and the mother has a responsibility to the child (until adulthood or transfer of that duty) because she is the one who brought the child into the world. Despite what you say, babies would not be able to survive very long in this world without someone taking care of it (proof is meet any newborn and read the stories of babies that ARE left to fend for themselves - spoiler: the ending is usually tragic). The mother brought the baby into the world and, therefore, she has the responsibility to make sure its rights are protected. She cannot expect anyone else to take care of it.