Prenatal Gene Tests Reveal More Fetal Abnormalities Than Conventional Methods, Studies Find

December 7, 2012 — Gene testing is more effective than traditional prenatal testing at revealing fetal abnormalities and identifying the causes of stillbirths, according to a pair of studies published on Thursday in the New England Journal of Medicine, the AP/Miami Herald reports.

Both studies compared the conventional method -- in which doctors examine cells from the placenta under a microscope for signs that indicate a dozen or so abnormalities -- with scanning with gene chips, which can detect hundreds of abnormalities.

Study Details

The first study assessed fetal samples from 4,400 women who sought screening for a variety of reasons, including having higher-risk pregnancies related to age, undergoing previous tests that suggested problems or having a general desire for more information.

The study found gene testing revealed problems in 6% of women whose ultrasounds indicated a possible structural defect but whose fetuses were declared normal by the conventional testing method. Gene tests also found abnormalities in nearly 2% of cases in which the mother was over age 35 or ultrasounds indicated an issue other than a structural defect.

The second study examined 532 pregnancies that ended in stillbirths. It found that gene testing revealed the cause of death in 87% of cases, compared with 70% of cases in which the conventional testing method was used. Genetic testing also provided couples with more detailed information on genetic abnormalities to help them determine whether future pregnancies would carry similar risks.

Implications for Practice

In an accompanying editorial, Lorraine Dugoff, a University of Pennsylvania high-risk pregnancy specialist, wrote that gene testing should become the standard of care for women whose ultrasounds suggest a structural problem.

Ronald Wapner, reproductive genetics chief at Columbia University Medical Center and lead author of the prenatal study, said that gene tests are not only useful for helping people decide whether to terminate a pregnancy, they also give women who continue their pregnancies more details about preparing for a child's special needs (Marchione, AP/Miami Herald, 12/5).