You are a woman over 35 years old.
You or your partner have a family history of a genetic disorder.
You or your partner have a close relative with mental retardation.
You have children with birth defects.
You have had a stillborn child, or three or more first-trimester miscarriages.
You or your partner belong to an ethnic group with a higher incidence of a particular disorder, such as Tay-Sachs, found in Jews of eastern and central European ancestry.
You and your partner are closely related.
You have been exposed to potentially dangerous substances.
A physician or midwife can take a detailed family, job, lifestyle and medical history to help determine the unborn babys potential for birth defects. Several recent technological advances offer the means for earlier prenatal diagnosis of genetic disorders. Tests such as amniocentesis, chorionic-villus sampling and maternal serum alpha-fetoprotein are routinely performed for women who have one or more of the characteristics described above. It is reassuring to know that over 90 percent of the time, the results of diagnostic tests are normal and the baby is born healthy.