We Need More Proof That Prenatal Gene Screens Are Beneficial

Expecting a baby often provokes mixed emotions—wonder and amazement but also concern. Will the child be healthy? Happy? Find his or her spot in the world? Several prenatal blood tests are now available that attempt to ease some of the anxiety—at least about health. By analyzing trace amounts of fetal DNA in a pregnant woman's bloodstream, these tests (which go by such names as Harmony, MaterniT21 PLUS and verifi) can identify various genetic anomalies up to six months before birth. Whether or not parents to be take advantage of these laboratory measures is, of course, up to them. But results from screening tests can be misleading, and industry and federal regulators are not doing enough to ensure that people get all the information they need.

At present, the tests detect major abnormalities—such as three copies of the 21st, 18th or 13th chromosome, which lead, respectively, to Down, Edwards and Patau syndrome. These measures are a definite safety improvement over earlier procedures to check the genes of the unborn. Previously such chromosomal abnormalities could be detected prenatally only by...