Prenatal Tests Target Unborn Babies with Down Syndrome

By Liz Townsend

During pregnancy, women undergo many tests to ensure the health of the baby and mother, screening for problems such as gestational diabetes and high blood pressure. However, unborn children are also tested for nonfatal, less severe problems. Those who are found to have conditions such as Down syndrome are almost always killed before they can draw their first breath.

A report in the February 28 issue of the Journal of the American Medical Association (JAMA) found that a very common method used to screen for Down syndrome is extremely unreliable. However, researchers continue to devote much time and money to develop other ways to diagnose Down syndrome, methods that can be done earlier in pregnancy with more accuracy.

People with Down syndrome, which is caused by the presence of an extra chromosome, often have mild to moderate mental retardation, congenital heart defects, and an increased risk for certain diseases, according to the National Down Syndrome Society (NDSS). Those with the syndrome can live full, productive, and happy lives with help from modern medicine and quality educational programs.

"People with Down syndrome are people first," insists the NDSS on its web site. They "have the same emotions and needs as their peers and deserve the same opportunities."

But prejudice and fear against those with Down syndrome are still very common. "Identification and selective abortion of Down syndrome pregnancies raise important ethical concerns," according to the National Institutes of Health's Guide to Clinical Preventive Services. "These concerns include the implicit message that Down syndrome is an undesirable state, the interpretation of induced abortion in eugenic terms by some persons, and societal and economic pressures that may stigmatize families with a Down syndrome member."

The drive to find new and better diagnostic tools that usually lead to the deaths of unborn babies with Down syndrome does nothing to alleviate such concerns.

The JAMA report analyzed studies concerning the use of second- trimester ultrasound tests that looked for physical "markers" thought to indicate the presence of Down syndrome. The markers included "a shaded area suggesting a thickening at the back of the neck" (or nuchal fold); "certain brain cysts; shortened thigh and upper-arm bones; bright spots on the bowel or heart; and high fluid levels in the kidneys," according to the Associated Press.

If any of these markers were found during the ultrasound examination, the pregnant woman would be encouraged to undergo further testing, usually an amniocentesis or chronic villus sampling. Both of these tests, which remove amniotic fluid or cells directly from the mother's womb, carry a real risk of miscarriage.

The report authors, led by Dr. Rebecca Smith-Bindman of the University of California at San Francisco, found that only one marker, a thickened nuchal fold, had even a slight amount of accuracy in predicting the presence of Down syndrome. There were many examples of false positives, cases in which the markers suggested the presence of Down syndrome but subsequent tests showed that the unborn child did not have the syndrome. If the ultrasound markers are used, the study authors wrote, "there will be inevitable losses of unaffected fetuses as a complication of amniocentesis."

"The markers, by themselves, aren't worth a whole lot," Smith- Bindman told the San Jose Mercury News. "They're very common, and we currently make a lot of decisions based on them. We're artificially creating anxiety and fear when there doesn't deserve to be any."

Many other tools are used or being developed to identify unborn babies with Down syndrome. One is a "triple test," in which the mother's blood is drawn during the first trimester of pregnancy and tested for levels of alphafetoprotein and two other substances that indicate the presence of Down syndrome.

A study known as "FASTER," the First and Second Trimester Evaluation of Risk, is currently being conducted at New York University, according to Reuters Health. Researchers are comparing second-trimester screening tests with an ultrasound examination for nuchal fold thickening in the first trimester combined with a maternal blood test.

Thirteen medical centers in the United States are conducting a federally funded clinical trial on a similar test, called the First Trimester Maternal Serum Biochemistry and Fetal Nuchal Translucency Screening, WebMD Medical News reported.

Other researchers are developing a "non-invasive genetic test that samples fetal cells in the mother's blood to screen for Down syndrome, but the test is not yet ready," according to the Mercury News.

It is clear that this research will result in more unborn children with Down syndrome killed in the womb, rather than helping find a cure or assisting those with the syndrome to live more healthy and happy lives. Advocacy groups insist that devoting energy to live-giving research would make a real and lasting difference.

"Ensuring equal treatment and access to services is a struggle that every family of a child with Down syndrome faces," states the NDSS. "A greater understanding of Down syndrome and advancements in treatment of Down syndrome-related health problems have allowed people with Down syndrome to enjoy fuller and more active lives."