 There are additional reasons to worry about the distortion of the gene pool that may result from long-term, routine prenatal testing. In a classic paper, “Moral Issues in Human Genetics”, Ruth Macklin (1977) points out that homogenizing or otherwise manipulating the gene pool may have dangerous effects that we do not presently understand and can't foresee. We don't know enough about how specific genes and mutations work to understand how they may be advantageous or disadvantageous at the population level. Furthermore, in eliminating a particular individual with some specific trait, we might be accidentally eliminating someone who has other traits that would have made her an exceptionally valuable member of society and contributor to the gene pool. (What if we had selectively aborted Abraham Lincoln in virtue of his Marfan syndrome, she asks? The fact that Lincoln probably did not have Marfan syndrome is beside the point.)