Typical pregnancy recommendations feature age old advice such as the need to increase folic acid intake, cut down – or eliminate – foods that contain mercury, kick vices such as smoking and drinking, and to provide a safe prenatal environment for your unborn child that is as stress and anxiety free as possible. What isn’t mentioned often in the same breath as this pregnancy-related advice is prenatal DNA testing, which is a non-invasive prenatal test that is often performed on mothers deemed to have increased risk criteria, such as advanced age or a familial history of certain genetic conditions. While this test can’t magically cure the condition, it can at least provide you an advanced look of what it entails, and what steps you and your family need to take in order to ensure that you are ready for this type of commitment.
What is Prenatal DNA Testing?
Prenatal DNA testing is a noninvasive prenatal test that uses fetal DNA found circulating throughout the mother’s bloodstream, known as cell-free DNA. This test allows a lab to screen for the presence of certain trisomies, such as Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome) and Trisomy 13 (Patau syndrome). Trisomies are genetic abnormalities defined by having a copy of a certain set of chromosomes present. These genetic defects are found through the presence of these abnormalities in the fetal DNA, which is why doctors often order the test when mothers are 35 and older, have a familial history of genetic abnormalities, have a positive serum screen and an ultrasound finding.
Trisomy 21 is the most common of the three, and will almost certainly lead to congenital heart defects, gastrointestinal disorders, and/or problems in the endocrine system, in addition to developmental disabilities that can range from mild to moderate. Although health conditions are common, those affected typically live rather long lives, with the average lifespan being about 56 years of age.
Trisomy 18 and 13 are much more severe, albeit more rare. Both conditions lead to significant physical and mental disabilities, with many of the fetuses dying before birth, and those that do survive living mere weeks or months after labor. There are few reports of Trisomy 18 and Trisomy 13 children surviving into their early teens, but this is incredibly rare and constitutes less than a quarter of one percent of all affected.
How Do I Get the Test?
If your healthcare professional deems you to be of an increased risk, he or she will order the test. The test requires a small amount of blood to be drawn from the mother, and then sent to a lab for screening and the sample can be taken as early as week 10 in your pregnancy. Your healthcare professional will generally have the results of this test within five days from the date the lab receives the initial sample.
What Will the Test Tell Me?
The test will tell you, conclusively, whether any of the above mentioned trisomies are present in the blood sample. It will also reveal the fetal gender, should you decide that you want to know. The test is designed to screen for the presence of trisomies 21, 18 and 13 without the risk of prenatal invasive procedures. What it won’t do is inform you of any specific health conditions related to these trisomies, such as congenital heart defects that are common in Trisomy 21 cases.
As I previously mentioned, the test isn’t intended to cure or treat any of these conditions, and positive tests may warrant the need for additional testing, but in a world that allows us the benefit of knowing so that we can be better prepared for any situation, it only makes sense to take advantage of it.