Down Syndrome Testing - What You Need to Know

Down syndrome is a genetic disorder that results in mild to severe disabilities, and is caused by an abnormality in the number of chromosomes an individual inherits from their parents. Chromosomes are the structures that carry our genes, which are small sections of DNA that determine how we grow and develop.

Typically, a person inherits two pairs of chromosomes, one from each parent, for a total of 46 chromosomes. Down syndrome occurs when the individual has an extra partial or whole copy of the twenty-first chromosome. This extra copy of chromosome 21 most often develops at the time of conception, as the result of a random abnormality during cell formation. However, Down syndrome may also be inherited from a parent – inherited diagnoses accounts for roughly one percent of cases.

Women over the age of 35 are known to have a higher prevalence of children affected by Down syndrome. If you’re expecting and worried that your baby may be born with Down syndrome, and would like more time to prepare for the birth of your child, tests are available to offer further insight into your pregnancy.

Down Syndrome Testing Options

There are two types of antenatal (before birth) tests for Down syndrome: screening tests, which allow your doctor to analyze the risk that your child will be born with Down syndrome; and diagnostic tests, which determine definitively whether your baby has the condition. If results from a screening test suggest a high risk of Down syndrome, diagnostic testing will most likely be recommended.

Screening tests, such as the noninvasive option MaterniT® 21 PLUS, screen for common trisomy disorders like Down syndrome, Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13), and many other conditions that can affect your baby’s health using only a blood draw.

Diagnostic tests, such as amniocentesis and chorionic villus sampling, require a sample obtained directly from the fetus in order to analyze the baby’s genetic material. These tests are typically performed after a screening indicates increased risk of Down syndrome.

Who Should Consider Testing for Down Syndrome?

It is important to note that Down syndrome testing is optional, and every couple has the right to decide whether they participate. However, some individuals may be at an increased risk of having a baby with Down syndrome.

It is commonly known that women of age 35 years or older at the time of conception are at an increased risk of having a child with Down syndrome. However, research has also shown that men over the age of 40 at the time of conception are also at an increased risk.

Additional risk factors include men and women who:

  • Have previously had a child with Down syndrome
  • Have a family medical history of Down syndrome
  • Carry a genetic translocation that, if passed down, will result in Down syndrome. A genetic carrier test can tell you whether you have this translocation. Ask your doctor if you think this might be a concern.

Learn More About Testing for Down Syndrome and Other Genetic Disorders

Learn more about your options by talking to your doctor or working with a genetic counselor. One of the best ways to discuss these options with your doctors is by downloading the informational PDFs and bringing these to your healthcare provider for more information. These healthcare professionals can help you understand your personal risk of having a child with Down syndrome or another genetic condition that can affect your baby’s health as well as carefully walk you through your testing options.