Non-invasive prenatal testing (NIPT) is a blood test performed during pregnancy that screens for certain chromosomal conditions in the fetus, most commonly Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13). It requires only a standard blood draw from the pregnant person’s arm, typically done at 10 weeks of gestation or later, and results usually come back within a few days.
How the Test Works
Throughout pregnancy, the placenta constantly sheds tiny fragments of DNA into the pregnant person’s bloodstream. This happens as part of normal cell turnover: placental cells go through a natural cycle of growth, aging, and replacement, releasing DNA fragments in the process. In a healthy pregnancy, grams of this placental material enter the maternal circulation every day. The DNA in these fragments closely reflects the fetus’s genetic makeup, since the placenta and fetus develop from the same fertilized egg.
NIPT works by collecting a blood sample and analyzing these free-floating DNA fragments. The blood contains a mix of the pregnant person’s own DNA (which comes mainly from blood cells and fat tissue) and the smaller portion from the placenta. Lab technology separates and counts these fragments, looking for abnormal amounts of DNA from specific chromosomes. If there’s more chromosome 21 material than expected, for example, that flags a higher chance the fetus has Down syndrome.
What It Screens For
The core purpose of NIPT is screening for the three most common chromosomal trisomies, conditions where the fetus has an extra copy of a chromosome. Trisomy 21 (Down syndrome) is the most reliably detected. Trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome) are also standard targets.
Many labs also offer screening for sex chromosome differences, such as Turner syndrome or Klinefelter syndrome. Current guidelines from the American College of Obstetricians and Gynecologists (ACOG), updated in late 2025, recommend that sex chromosome screening be available as an opt-in option with counseling beforehand, rather than included automatically.
Some labs market expanded panels that screen for smaller chromosomal deletions, like 22q11.2 deletion (DiGeorge syndrome). However, the accuracy of NIPT for these microdeletion conditions is significantly lower and remains controversial. ACOG does not recommend routine screening for any microdeletion condition. If you want information about these rarer genetic changes, diagnostic testing (not NIPT) is the more reliable path.
How Accurate It Is
NIPT is the most sensitive and specific screening test available for the three main trisomies. For trisomy 21, studies show sensitivity around 93% and specificity around 96%. For trisomy 18, those numbers are roughly 89% and 96%. Trisomy 13 detection is less reliable, with sensitivity closer to 74%, though specificity is very high.
These numbers sound reassuring, but what matters most in practice is the positive predictive value (PPV): if your test comes back high-risk, what are the chances the result is correct? This depends heavily on your baseline risk, particularly your age. In one large study, women 35 and older who received a high-risk result had a PPV of about 65%, meaning roughly two-thirds of positive results were confirmed. For women under 35, that figure dropped to about 46%, meaning more than half of high-risk results turned out to be false positives. The takeaway: a high-risk NIPT result is not a diagnosis, especially for younger patients.
Screening vs. Diagnostic Testing
This is the most important distinction to understand. NIPT is a screening test. It estimates probability. It cannot confirm or rule out a chromosomal condition with certainty. Diagnostic tests, specifically amniocentesis and chorionic villus sampling (CVS), analyze actual fetal or placental cells and provide definitive answers.
If NIPT returns a high-risk result, the next step is confirmatory diagnostic testing. CVS can be done earlier in pregnancy (typically 10 to 13 weeks) by sampling a small piece of placental tissue. Amniocentesis is performed later (usually 15 to 20 weeks) by withdrawing a small amount of amniotic fluid. Both carry a small risk of miscarriage, which is why many people prefer starting with NIPT as a non-invasive first step. Some experts favor amniocentesis for confirmation after a high-risk NIPT, particularly when no structural abnormalities are visible on ultrasound, because it avoids the complicating factor of placental mosaicism that can occasionally affect CVS results.
What Can Cause Inaccurate Results
Several biological factors can throw off NIPT results. One common cause of false positives is a “vanishing twin,” where a second embryo stopped developing early in pregnancy. The tissue from the lost twin can continue releasing DNA fragments into the bloodstream for weeks, sometimes 7 to 8 weeks or longer, skewing the chromosome counts. This effect can persist into the second trimester but generally fades by 12 to 14 weeks after the twin stops developing.
Confined placental mosaicism is another source of error. This occurs when the placenta contains cells with a chromosomal abnormality that the fetus itself doesn’t have. Since NIPT reads placental DNA, not fetal DNA directly, the test reflects whatever the placenta contains. Higher maternal body weight can also be a factor, because it tends to dilute the proportion of placental DNA in the blood sample (called the fetal fraction), making the test harder to read accurately. When the fetal fraction is too low, the lab may report a “no result” rather than risk an unreliable reading.
When You Can Get Tested
NIPT is routinely offered from 10 weeks of gestation onward. Before that point, the amount of placental DNA circulating in the blood is generally too low for reliable analysis. Some newer lab technologies have shown the ability to detect fetal sex as early as 6 weeks, but these applications are still limited and not yet standard for chromosomal screening. For most people, the test fits naturally into the schedule of first-trimester prenatal visits.
Results typically take a few days to about two weeks, depending on the lab. The blood draw itself is identical to any routine blood test.
Who Should Be Offered NIPT
Current ACOG guidance, endorsed in November 2025, recommends that NIPT for the three common trisomies be routinely available to all pregnant patients, regardless of age or risk level. This is a shift from earlier guidelines that prioritized it for women over 35 or those with other risk factors. The updated position recognizes NIPT as the most sensitive screening option available and affirms that every patient has the right to pursue or decline it after appropriate counseling.
For twin pregnancies, NIPT is recommended as a first-line screening option for trisomy 21, 18, and 13. Screening for sex chromosome conditions in twins, or any screening in pregnancies with three or more fetuses, is not currently recommended due to limited data.
Cost and Insurance Coverage
The list price for NIPT ranges from roughly $1,100 to $1,590, but most labs offer self-pay pricing between $299 and $349, and some provide additional financial assistance. Insurance coverage is inconsistent. Many private insurance plans do not cover NIPT for pregnancies considered low-risk, leaving patients responsible for deductibles, co-pays, or the full cost. Paradoxically, in some states, public insurance like Medicaid covers NIPT for low-risk pregnancies at no cost. One study found that women with public insurance were more than three times as likely to choose NIPT as their initial screening compared to women with private insurance, largely because cost wasn’t a barrier.
If you’re considering NIPT and cost is a concern, it’s worth calling both your insurance company and the testing lab directly. Many labs will verify your coverage in advance and can quote your out-of-pocket responsibility before you commit.