From a legal position, the pater familias alone has the right of life and death over his gens with no gainsaying. The State has no business interfering in the affairs of the family. If the family disagrees with the decision of one of its women to abort or to expose their infant, it is their affair to handle in their own manner. Progeny are continuities of life of the begetters and if the begetters don't consent to the continuance of the begotten, I don't think there's necessarily any inherent "right" for the begotten to continue to exist. Wolves cull themselves, man.
On the other hand, acting in such a fashion (read: killing of any kind) continues to play the game and allows the decline of the being to non-human realms. If any individual aspires higher than the mixed kamma of humans, one shouldn't engage in killing, or getting others to kill for you.