When we accept as a principle that a being can be given existence because it is the object of desire, we necessarily say that a being can be deprived of existence because it is not the object of desire.
The unwanted infant can be eliminated for the sole reason that it is not desired. The child who doesn't conform to the qualities required can also be eliminated for the sole reason that he doesn't have the qualities required of him.
This explains the fact that the indications for abortion have a tendency to vary and multiply. The multiplication of "eugenic" or "orthogenic" indications for abortion are the corollary of a vision that reduces the infant to an object of desire.