That access, until recently, has required invasive procedures like amniocentesis. But last week brought a remarkable breakthrough: a team of scientists mapped nearly an entire fetal genome using blood from the mother and saliva from the father.

The procedure costs tens of thousands of dollars today, but the price will surely fall. And it promises access to a wealth of information about the fetus’s biology and future prospects — information that carries obvious blessings, but also obvious temptations.

Thanks to examples like Irving Fisher, we know what the elites of a bygone era would have done with that kind of information: they would have empowered the state (and the medical establishment) to determine which fetal lives should be carried to term, and which should be culled for the good of the population as a whole.

That scenario is all but unimaginable in today’s political climate. But given our society’s track record with prenatal testing for Down syndrome, we also have a pretty good idea of what individuals and couples will do with comprehensive information about their unborn child’s potential prospects. In 90 percent of cases, a positive test for Down syndrome leads to an abortion. It is hard to imagine that more expansive knowledge won’t lead to similar forms of prenatal selection on an ever-more-significant scale.