What is Down Syndrome?

All women, irrespective of age, are at risk for giving birth to a child with birth defects. For example, in the state of California 1,600 children are born each day, with 50 having a major birth defect. Of these 50, two will have Down Syndrome. Click this link to review information regarding the child with Down syndrome (trisomy 21).

Down syndrome is associated with varying degrees of mental retardation, and may have additional abnormalities of the head, hands, brain, heart, kidneys, stomach and intestines. The risk for Down syndrome, as well as other chromosomal abnormalities, increases with advancing maternal age.

The diagnosis before birth of Down syndrome is made by analyzing chromosomes obtained from cells in the amniotic fluid or the placenta. To obtain these cells for analysis requires either amniocentesis or chorionic villus sampling, invasive tests which can cause miscarriage. For this reason, these invasive procedures have been offered only to patients who have been at high risk for Down syndrome. High-risk women have been defined as those who have a risk (1 in 270) equal to or greater than a woman 35 years of age.

Until recently, women in this age group only had one option---invasive testing with its associated risk of miscarriage. Recent studies, however, have suggested that additional screening tests, coupled with maternal age, can be used to decrease the risk for Down syndrome as well as other chromosomal abnormalities. Using these screening tests results in a high detection rate of Down syndrome, while at the same time decreasing the number of amniocenteses and the subsequent loss of normal fetuses.