A new study sets the stage for wider use of gene testing in early pregnancy. Scanning the genes of a fetus reveals far more about potential health risks than current prenatal testing does, say researchers who compared both methods in thousands of pregnancies in the U.S.

A surprisingly high number — 6% — of certain fetuses declared normal by conventional testing were found to have genetic abnormalities by gene scans, the study found. The gene flaws can cause anything from minor defects such as a club foot to more serious ones such as mental retardation, heart problems and fatal diseases.