Posted: Mar 31, 2012 9:22 PM
 
With the development of a new prenatal blood test to detect Down syndrome, many pregnant women may be able to avoid the more invasive and risky amniocentesis.

In the fall of 2011, Sequenom, Inc. announced that a new prenatal Down syndrome blood test would be available for pregnant woman in 20 cities around the U.S., marking the first time women could undergo a Down syndrome test without an invasive amniocentesis or chorionic villus sampling (CVS). In February 2012, another blood test, this time developed by Aria Diagnostics, was announced. This test can detect both Down syndrome and Edwards syndrome -- a genetic disorder than can cause severe birth defects and is often fatal.

When to get tested?

Some screening tests can be done during the first trimester to determine if you are at a high risk of carrying a Down syndrome baby. Keep in mind that the incidence of Down syndrome increases with the age of the mother. An ultrasound can be done in the late first trimester to measure a specific region of the back of the baby's neck. More fluid tends to be present in this area if there is an issue. A blood test to look for abnormal levels of pregnancy-associated plasma protein-A (PAPP-A) and human chorionic gonadotropin (HCG) may indicate an issue.

With these newly developed blood tests, which are generally done in the second trimester, women could eliminate the more risky and invasive procedures.

If these pre-screening tests show that there may be a problem, then some women elect to have further diagnostic tests after the 15th week of pregnancy -- such as the aforementioned amniocentesis or CVS, which is typically performed in the ninth and 14th weeks. Both of these tests carry a risk of miscarriage -- approximately one in 200 for the amniocentesis and about half that for the CVS.

With these newly developed blood tests, which are generally done in the second trimester, women could eliminate the more risky and invasive procedures.

Will blood testing become the norm?

Though this type of testing is still relatively new, it could become the norm if costs are reasonable and results are accurate. As more and more companies develop prenatal blood tests for Down syndrome, it will likely drive the price down due to the competition. Sequenom has indicated that its test won't cost pregnant mothers more than $235 in out-of-pocket costs.

Will fewer babies with Down syndrome be born?

One effect of an invasive, relatively low-cost blood test becoming available to the masses is that the number of Down syndrome babies born is likely to decrease. Many parents choose to abort when a fetus is diagnosed with Down syndrome. To learn more about the blood test to detect Down syndrome, talk to your health care provider.

More about the second trimester

Second trimester ultrasound: What to expect
Finding out the gender: Yay or nay?
How much caffeine is safe during pregnancy?

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