Noninvasive prenatal testing, commonly called NIPT, is a screening blood test performed during pregnancy that analyzes small fragments of DNA circulating in a pregnant person’s blood. This cell-free DNA comes from the placenta and reflects the genetic makeup of the developing baby. NIPT is used to estimate the risk that a fetus may have certain chromosomal conditions, and it can be done as early as 10 weeks into pregnancy.
What NIPT Screens For
NIPT primarily screens for the most common chromosomal conditions caused by an extra or missing copy of a chromosome. These include trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patau syndrome). Many NIPT panels also screen for sex chromosome differences, such as Turner syndrome or Klinefelter syndrome, and can reveal the baby’s sex if you choose to know.
Some expanded NIPT panels offer screening for certain microdeletions, which are small missing pieces of a chromosome. The most common of these is 22q11.2 deletion syndrome. However, screening for microdeletions is not currently recommended as routine by the American College of Obstetricians and Gynecologists (ACOG), and the accuracy of these expanded screens is lower than for the common trisomies.
Who Should Be Offered NIPT
In 2020, ACOG and the Society for Maternal-Fetal Medicine updated their guidelines to recommend that prenatal genetic screening, including NIPT, be discussed with and offered to all pregnant patients regardless of age or baseline risk. Previously, NIPT was primarily offered to women who were 35 or older or who had other known risk factors for chromosomal abnormalities.
This shift reflects the understanding that chromosomal conditions can occur in any pregnancy. ACOG also recognizes NIPT as the most sensitive and specific screening test available for the common trisomies, with a significantly lower false-positive rate compared to traditional serum screening with or without nuchal translucency ultrasound. If you are planning a pregnancy or are newly pregnant, preconception counseling is a good time to discuss screening options with your provider.
It is important to know that NIPT is entirely optional. Your provider should walk you through what the test can and cannot tell you so that you can make a decision that feels right for your family.
How Accurate Is NIPT?
NIPT has a very high detection rate for trisomy 21, generally above 99%, with a false-positive rate of less than 0.1%. Detection rates for trisomy 18 and trisomy 13 are also high, though slightly lower. While these numbers are reassuring, NIPT is a screening test, not a diagnostic test. That means it estimates risk rather than providing a definitive answer.
A low-risk result significantly reduces the chance that the baby has one of the screened conditions, but it does not guarantee the baby is unaffected. Similarly, a high-risk result does not confirm a diagnosis. If your NIPT comes back positive or high-risk, your provider will recommend genetic counseling and may offer diagnostic testing such as chorionic villus sampling (CVS) or amniocentesis to confirm the result.
In some cases, the lab may not be able to return a result at all. This is called a “no-call” result and can happen for reasons like low fetal DNA in the blood sample or high maternal body weight. A no-call result may be associated with a slightly increased risk of aneuploidy, a genetic condition featuring an abnormal number of chromosomes (missing or extra) in cells, so your provider will discuss next steps, which could include redrawing the blood or moving to diagnostic testing.
What Happens After You Get Your Results
If your results come back low-risk, you can feel reassured that the likelihood of the screened conditions is very low. Your provider will continue with routine prenatal care, including a second-trimester anatomy ultrasound typically performed between 18 and 22 weeks.
If your results come back high-risk, try to remember that a positive screen is not a diagnosis. The next step is usually a referral for genetic counseling, where a specialist will help you understand the result, discuss your options, and support you through any decisions about further testing. Diagnostic procedures like amniocentesis carry a small risk but provide a definitive answer.
No matter what your results show, the goal of NIPT is to give you and your care team information early in your pregnancy so you can plan, prepare, and make informed choices about your care.
Feeling Informed Makes All the Difference
It is completely normal to feel nervous about prenatal testing. Having a clear understanding of what NIPT does, what it does not do, and what your results mean can go a long way toward easing that anxiety. Your OB/GYN is your best resource for talking through whether NIPT is a good fit for your pregnancy. If you are pregnant or planning to become pregnant and want to learn more about your screening options, schedule a visit with your provider at Bloom OB/GYN by calling (202) 449-9570 or visiting bloom-obgyn.com/request-appointment.
