"Discrimination in employment on account of age is now forbidden by federal law which enunciates a strong public policy. And while age may be a reasonable criterion for determining the right to vote or to drive a car, it can hardly be contended that it is a reasonable basis for determining whether one has a right to continue living. The child in the womb should have the same right as his older brother or sister not to be killed where it is unnecessary to save the life of his mother. Nor should the fact that he temporarily reposes in his mother’s womb rather than in an incubator or a crib operate to deprive the child of the right to continue living...."