Prenatal genetic diagnosis.

More than 100,000 children are born in the U.S. each year with major congenital defects or genetic disorders, with or without mental retardation. Advances in prenatal diagnosis have now made it possible to detect an increasing number of these disorders in utero. Carrier detection is advised prior to pregnancy, rather than after the birth of a defective child, or during pregnancy itself. Patients have a right to know about their genetic risks and should have the freedom to exercise their options.