Amniocentesis was developed as a therapeutically-oriented procedure, and still is when performed in the third trimester of pregnancy. But mid-trimester amniocentesis (14th to 18th week) is at present applied only for eugenic reasons: (1) to determine the sex of the baby, (2) to diagnose the presence and nature of a chromosomal disorder, (3) to diagnose an inborn error of metabolism by an appropriate enzyme assay on cells cultured from amniocentesis-obtained fluid.

Since most of the diseases that can be diagnosed in this way are not treatable as yet, antenatal diagnosis is used only to inform the parents and/or facilitate selective abortion of defective babies or carriers. It is obvious that ethical principles must be applied to human acts such as these. These principles applied depend on the philosophical and religious views one brings to bear on such problems.

It is suggested that standards derived from a secular humanist philosophy, such as the ‘good’ of society, familial or parental ‘good’, a ‘natural’ standard such as ‘quality of life’, are all inadequate and indeed dangerous.

The argument is presented that these grave issues can safely be resolved only in an ethical system that is based on optimal value judgements; they will be optimal if they are informed by a sound metaphysics of being, and suffused by the light of a vision of man derived from Divinely-revealed truth as transmitted chiefly by the teaching authority of the Church founded by God.