A simple blood test can tell doctors more about your baby than ever before.
Learn about the test that’s making genetic screening more reliable.
Did you know that pieces of your baby’s DNA circulate in your bloodstream? Noninvasive prenatal testing (NIPT) involves a simple blood screening that analyzes that DNA (it’s called cell-free DNA, or cfDNA) to pinpoint a baby’s risk for a number of genetic disorders, including Down syndrome.
What is noninvasive prenatal testing (NIPT)?
NIPT is a prenatal screening, which looks at DNA from your baby’s placenta in a sample of your blood to identify whether you’re at increased risk of giving birth to a child with a genetic disorder. A screening like NIPT cannot, however, determine for sure whether your baby actually has a chromosomal disorder, only the likelihood of having that condition. But even though it can’t tell for sure whether your baby has a genetic abnormality, it is highly accurate — 97 to 99 percent accuracy for three of the most common conditions.
The results of a NIPT screening can help you and your doctor decide the next steps, including whether to have a diagnostic test like chorionic villus sampling (CVS) or amniocentesis (“amnio”). These genetic tests analyze a baby’s own genetic material, collected from the amniotic fluid or placenta, to tell with 100 percent certainty whether a baby has a chromosome abnormality. However, they are invasive, which means they slightly increase the chance of miscarriage.
How is NIPT done?
Because a NIPT involves only a quick blood draw with a needle and syringe, it’s safe for you and your baby. All you’ll need to do is offer up your arm at the doctor’s office or a lab. Your sample is then sent to a lab, where a technician will look at the cfDNA in your blood for signs of abnormalities.
Once the results of your NIPT are back, your doctor will likely pair them with the results of your first-trimester ultrasound or nuchal translucency screening to determine whether further testing is needed. Depending on the results, your doctor may recommend following up with amniocentesis or CVS to confirm the result and check for other problems NIPTs can’t detect.
What does the NIPT screen for?
All NIPTs screen for the most common chromosomal disorders:
- Trisomy 21 (Down syndrome)
- Trisomy 18 (Edwards syndrome)
- Trisomy 13 (Patau syndrome)
Since the test looks at a sample of your blood, some researchers think it may eventually also be a screening tool for moms, too. In one study, some NIPT results indicated a baby was at risk for a genetic problem. But later it was clear the baby was not at risk and the results were actually indicating the early onset of cancer in the mom. The findings need further research before practitioners begin using the tests for this purpose — but because the test could potentially detect early-stage cancer before symptoms are apparent, it could help women get further diagnostic tests and care earlier when it’s more effective.
What are the different kinds of NIPTs?
There are a few companies that currently offer noninvasive prenatal testing. Each company offers slightly different panels screening for various genetic disorders. Some screen for abnormalities including triploidy and microdeletion.
It’s worth noting that while some brands companies between maternal and fetal cfDNA, others do not (which means they’re less accurate), so you might want to ask your practitioner which type of test she uses.
When is NIPT done in a pregnancy?
NIPT can be performed any time after 9 weeks into your pregnancy — earlier than any other prenatal screening or diagnostic test. In comparison, nuchal translucency screening is done between weeks 11 and 13; CVS is done at 10 to 13 weeks; the quad screen is completed between weeks 14 and 22; and amniocentesis is usually performed between weeks 16 and 18, though it’s sometimes done as early as week 13 or 14 and as late as week 23 or 24.
How accurate is NIPT?
Research suggests that NIPTs create fewer false alarms than standard first-trimester blood screenings (like first-trimester bloodwork or quad screening) that measure hormones and special proteins in Mom’s blood. Other research has shown that NIPTs are more accurate than those same standard screenings in predicting the risk of Down syndrome (NIPTs are 99 percent accurate) and Edwards syndrome.
Should you get NIPT?
In the past, NIPTs were only recommended for women at high risk for carrying a baby with a chromosomal abnormality — like moms-to-be who are 35 or older, previously had a child with a genetic disorder or have a family history of these conditions — or if there was a concern about the result of another prenatal test.
ACOG (American College of Obstetricians and Gynecologists) now recommends that doctors discuss all screening options with all pregnant women — regardless of age or risk — to figure out which one, if any, is most appropriate. The decision is a personal one, and this counseling phase is important. Just because a test was right for a friend doesn’t mean it’s right for you. Be sure to ask your health care provider to spend some time going over all your choices. Considering how quickly the science is evolving, the guidelines about which screenings are best for you may change.
Before you get tested, double-check with your insurance company to find out if NIPT is fully covered — and if not, what it will cost you.
Also, while getting this test done is far from scary (unless you really hate needles), you may be nervous about seeing the results. If this is the case for you, consider talking to your doctor or to a genetics counselor about what positive test results could mean for you and your baby. For many parents, knowing as much as possible as soon as possible is better. Finding out about potential conditions early on allows you to prepare for a special needs baby and make plans to deliver at a facility that can better address your and your baby’s health needs right away.
Source: whattoexpect.com