TESTING DURING PREGNANCY FOR DOWN SYNDROME
During pregnancy, you can test for whether you baby may have Down syndrome. In each cell of the human body, there are 23 pairs of chromosomes. Down syndrome occurs when a baby has an extra copy of chromosome 21. For this reason, some people refer to Down syndrome as “trisomy 21.” Children born with Down syndrome can face intellectual disabilities, developmental challenges, and health problems. For this reason, many health facilities offer tests in advance so that parents can prepare for any issues as early as possible.
There are two categories of prenatal tests for Down syndrome:
• Screening Test – This test tells you whether there is an increased chance that the baby has Down syndrome. For instance, you may discover that there is a 1 in 100 chance your child has Down syndrome. Screening tests do not harm the mother or baby. If there is a high likelihood that your child has the condition, medical providers usually advise moving on to the diagnostic test.
• Diagnostic Test – This test gives you a definitive answer (a clear “yes” or “no”) on whether your child has Down syndrome. Since this test is harder to take, most medical providers only offer it after a woman showed high likelihood on the screening test.
If you need help understanding how to care for a child with Down syndrome, The Warren Center is here for you. We offer host of support services to improve the outlook of children born with Down syndrome. For more information, contact us.
TYPES OF SCREENING TESTS
TYPES OF SCREENING TESTS
There are three types of screening tests for Down syndrome:
First Trimester Combined Test
Mothers can receive this one anywhere between week 9 to week 14 of pregnancy. It consists of two parts:
- Blood Test – The doctor looks for “markers” that might indicate Down syndrome. These can include levels of proteins, hormones, or other substances that can suggest an issue with the baby’s chromosomes.
- Ultrasound – In this part, doctors look at the area behind the neck called the nuchal fold. The fluid in this area is called nuchal translucency. If fluid levels are higher than normal, this could indicate Down syndrome.
Integrated Screening Test
Some healthcare providers call this one the second trimester test, the maternal serum screen (MSS), or the “triple test.” The first step is just like the first trimester combined test. Then anywhere from 14 weeks to 22 weeks, you will also receive a blood test called the quad screen. This blood test looks for four different markers that can be signs of Down syndrome.
In addition to an integrated screening test, most pregnant women have a morphology scan (also known as the anomaly scan) between 18 weeks and 22 weeks into the pregnancy to receive an update on the baby’s growth and to see how the pregnancy is progressing. The morphology scan is another way that doctors can look for signs of Down syndrome.
Non-Invasive Prenatal Testing (The Cell-Free DNA Test)
The non-invasive prenatal test (NIPT) involves a simple blood draw that analyses DNA from the baby that has passed into the pregnant woman’s bloodstream. You can take this test starting at 10 weeks, but most healthcare providers reserve this exam for pregnant women with a higher likelihood of having a baby with Down syndrome.
TYPES OF DIAGNOSTIC TESTS
TYPES OF DIAGNOSTIC TESTS
Diagnostic tests examine the baby’s chromosomes for a clear sign of Down syndrome. A positive test result means that the baby most likely has Down syndrome. Negative test results mean that your baby most like does not have the condition. Since diagnostic tests increase the mother’s chances of having a miscarriage, most doctors only perform them after the initial screening tests or on women with a family history of genetic conditions.
There are three types of diagnostic tests for Down syndrome:
Amnio tests examine a sample of the amniotic fluid that surrounds your baby in the womb. The doctor retrieves the sample by inserting a needle into the abdomen. The retrieval process takes around 20 minutes. This test looks for missing, extra, or abnormal chromosomes. The test usually occurs between 15 weeks and 18 weeks of pregnancy. Risk for miscarriage is about 1 in 100 (or around 0.6%), with the risk being higher if the amnio test occurs before 15 weeks.
Chorionic villus sampling (CVS)
The CVS tests a sample of the placenta for missing, extra, or abnormal chromosomes. The doctor retrieves the sample through the cervix or by inserting a needle into the abdomen. The retrieval process takes around 20 minutes. This test can take place between 10 weeks to 12 weeks, but there is a risk for miscarriage or other complications,
Also known as percutaneous umbilical blood sampling (PUBS), cordocentesis is a test in which the doctor takes blood from the umbilical cord to look for chromosomal abnormalities. This test can take place between 18 weeks and 22 weeks. Chances of miscarriage range from 1.4% to 1.9%, so this exam is usually a last resort for definitive results.