Down syndrome is a chromosome disorder. A baby typically receives 23 pairs of chromosomes from each parent, for a total of 46. If your baby has Down syndrome, it means they have 47 chromosomes, with an extra copy of the 21st.
This disorder causes your baby to have distinctive physical features and developmental delays.
Your provider might recommend screening for Down syndrome if you have certain risk factors. One of the biggest factors that can increase the chances of having a baby with Down syndrome is being over age 35 when you get pregnant. Other factors include having another child with Down syndrome or other family history, according to Mayo Clinic.
But more and more, women are choosing to screen regardless of their age or family history. According to a 2016 study in the journal Obstetrics and Gynecology, 78 percent of pregnant patients choose to have genetic screening performed during their pregnancy. This is partly because screenings have become more accessible. In 2020, the American College of Obstetricians and Gynecologists updated its guidelines to suggest that all pregnant people receive screening regardless of risk factors.
Most genetic testing done during pregnancy is covered by insurance, but you’ll want to make sure to check on your specific coverage. Depending on which type of screening you have, you may have to pay some or all of the out-of-pocket costs.
What’s the difference between screening and diagnostic testing?
First, it’s helpful to understand the differences between a *screening* and a *diagnostic* test.
Screenings are usually done via a blood test or ultrasound and tell you only whether your baby has a higher or lower chance of Down syndrome. A positive screen is not the same as a diagnosis, and it doesn’t mean, for example, that your baby has Down syndrome. If you get a positive screening, you need to have further testing in order to confirm a diagnosis.
Diagnostic testing is often done if you have a screening that showed a possible chance of having a baby with Down syndrome. These tests are usually more involved and performing them brings a slightly increased risk for miscarriage.
Not all screenings are created equal
There are several screening options to choose from.
First-trimester screening: A combination of both a blood test and ultrasound exam typically done at the same time between 10 and 13 weeks. For the blood test, your provider is looking for certain “markers,” which are proteins or other substances in your blood that can indicate Down syndrome.
The ultrasound measures the fluid at the back of your baby’s neck, in an area known as the nuchal fold. Higher levels of fluid can indicate that your baby has an increased chance of having Down syndrome.
Second-trimester screening: This screening also involves an ultrasound between 18 and 22 weeks, as well as a blood test, known as the “quad” screen. Whereas the first-trimester blood test looks at two markers, the second-trimester blood test looks at four. The quad screen is done between 15 and 22 weeks. According to Mayo Clinic, your provider might use first-trimester screening results together with second-trimester results to more accurately detect Down syndrome.
Integrated screening: Integrated screening combines first- and second-trimester screenings as well as screening for neural tube defects such as spina bifida. The first blood test is done at 10 to 13 weeks and the second is performed between 15 and 16 weeks. The ultrasound is done in the first trimester at the same time as the blood test.
Cell-free DNA testing: Also known as NIPS, you can have this screen done if you’re at least 10 weeks. This type of blood test looks at DNA from both you and your baby and is screened for several chromosome conditions including Down syndrome. Cell-free DNA screening can be more accurate than first- and second-trimester screenings.
Does brand matter?
There are several companies that perform screenings. You might wonder whether the brand matters. Two of the most common are:
- Myriad Genetics, formerly Counsyl offers tests under the name Prequel.
- Sequenom, which is owned by Labcorp, offers another common testing option called MaterniT21.
Other companies that offer screenings are Progenity’s Innatal test; Natera’s Panorama test; and the Harmony test. So are they doing anything different?
Because screening does not require FDA approval, these companies are all self-verified. That makes it difficult for standardized data. However, the companies do release their own data:
| Sensitivity | Specificity | |
| Myriad Prequel | 99.7% (Confidence interval: 99.1-99.9%) | 99.96% (Confidence interval: 99.93-99.98%) |
| Sequenom MaterniT21 | 99.1% (Confidence interval: 96.3-99.8%) | 99.9% (Confidence interval: 99.6-99.9%) |
If you’re making a choice between these, then, it may come down to insurance coverage and availability. Out of pocket costs will vary.
What to know about the screening process
The screening process for Down syndrome is pretty straightforward, but it depends on which type of screening you have done. You’ll have to factor in the costs of the screenings, as well as whether you want screening during the first or second trimester, or both.
Blood tests involve a simple blood draw in the lab and you shouldn’t have to fast. The ultrasound will feel similar to your routine ultrasounds in pregnancy. It uses sound waves to make an image of the baby on a screen. You’ll lie on an exam table with your top pulled up and the technician uses a gel to move the wand around easier. They’ll take measurements of your baby, so feel free to ask questions and have them point out for you what they’re looking for.
When you get your results depends on the clinic and provider. It takes about a week to get your cell-free DNA results. If you have the integrated screening done, you’ll typically have to wait until your second-trimester results come back.
You received your results. Now what?
A negative result means your baby is at a lower risk of having Down syndrome. It doesn’t mean your baby doesn’t have a genetic condition, however. Likewise, a positive result doesn’t mean your baby has Down syndrome. It just means they’re at a higher risk of the disorder than other babies in general. As with other screenings, there are chances of having a false positive or negative, meaning you receive an inaccurate result.
Getting a positive screening result can understandably cause anxiety and worry. But try not to stress. Remember, screening isn’t conclusive, and further testing is needed in order to confirm the results.
If you do need diagnostic testing to confirm or rule out Down syndrome, you may have an amniocentesis or chorionic villus sampling (CVS). Amniocentesis involves a needle inserted through your abdomen to take a sample of amniotic fluid. In CVS, a sample is taken of the placenta to test in a laboratory.
If it’s confirmed you have a baby with Down syndrome, knowing sooner can help you prepare and find support. For some parents, having time to digest this information early on can give them more time to have the resources in place for caring for a child with Down syndrome.
Talk with your healthcare provider about your concerns or if you’re interested in screening for Down syndrome or other genetic conditions. Keep in mind, you don’t have to do screening at all in your pregnancy. It’s important to have the conversation with your provider so that you are armed with the information you need to make a decision right for you.