What is an NIPT Test?

Published on August 17th, 2020 and Updated on April 1st, 2021


Around ten to twelve weeks into pregnancy, your doctor might discuss taking an NIPT, or a noninvasive prenatal test, with you. This noninvasive prenatal screening is used to screen for chromosome abnormality in your growing baby. At the same time, it also lets you answer that all-important question: is it a boy or girl? 

If this puts a sparkle in your eye and gets you daydreaming about the ultimate gender reveal party, there’s something to consider before taking a gender prediction test. NIPT tests are elective tests that not all pregnant women take, and there are different types of NIPT tests to be aware of.

How an NIPT Works

When you’re pregnant, you share just about everything with your baby, forming an inseparable bond. You share meals (nutrients) and your breath (oxygen) through the umbilical cord. And you even share the same bed at night. 

You also share your veins’ real estate

Within your bloodstream you hold both your own DNA and your baby’s DNA. Your baby’s DNA is cell-free fetal DNA, or cffDNA for short. Little bits of cffDNA pass through the placenta into your bloodstream. This means a blood sample from you also contains the genetic material of your growing child. The percent of cffDNA in your blood is known as the fetal fraction, which increases the further along you are in pregnancy. Around 10-12 weeks, the fetal fraction becomes high enough (above 4%) for an NIPT to accurately screen for chromosomal abnormalities in your baby’s DNA.

In short, the NIPT is a simple test using a blood sample from mom to screen baby’s DNA for a chromosomal disorder, a genetic condition, or abnormalities. 

What Does NIPT Test For?

The NIPT screens baby’s DNA for two types of chromosomal abnormalities. The more common abnormality is a duplicated chromosome (known as a trisomy). Less common is a missing or partially missing chromosome (known as a monosomy). 

The more frequent chromosomal abnormalities include:

  • Down syndrome – Also known as trisomy 21, Down syndrome affects how both the body and brain develop. It can often result in a flattened face, poor muscle tone and joints, lower IQ, and various other health problems.
  • Edwards syndrome – Also known as trisomy 18, Edwards syndrome is characterized by a low birth weight. Problems continue after birth, resulting in heart defects, small jaw, and overlapping fingers.
  • Patau syndrome – Also known as trisomy 13, Patau syndrome is associated with intellectual disabilities and physical defects of the heart, brain, and spinal cord.
  • Turner syndrome – A female-specific condition, Turner syndrome occurs when one of the sex chromosomes is missing entirely or partially. This results in a shorter stature, undeveloped ovaries, and heart defects. 
  • Klinefelter syndrome – Klinefelter syndrome occurs in males who have more than one X chromosome. This can result in underdeveloped testicles and infertility.

This isn’t all that’s revealed. Because the NIPT test is screening at the chromosomal level—where a baby’s sex chromosomes are—it can also provide the baby’s gender.

Who Receives an NIPT? 

As mentioned, not all women will be recommended this elective test by their doctor. There are a few indicators that doctors will use to determine who should be given an NIPT.

If the maternal age (the age of mama at the time of delivery) is 35 or higher. As women age, there is a higher chance of various complications with pregnancy. The specific age of 35 came about because it used to be the age in which the risk of having a child with the chromosomal condition trisomy 21 (Down syndrome) was equal to the risk of miscarriage through amniocentesis. Today, the risk of miscarriage during amnio is much lower (around 1 in 500), but the age of 35 has seemed to stick.

If there is a history of any of the chromosomal abnormalities within the maternal or paternal family. Because these conditions are genetic, they’re hereditary (or passed through family genes). If someone in the family has Down syndrome, for example, the likelihood that a child within the extended family will also have this chromosomal anomaly is higher.

If prior pregnancies have revealed a high chance for chromosomal abnormalities. In this instance, an NIPT will be recommended for all future pregnancies.

Note: This elective NIPT test ordered by a doctor is what’s usually referenced when people discuss non-invasive prenatal testing. However, there is another type of NIPT (discussed below) that solely looks at gender and can be taken earlier than 10 weeks.

Results of an NIPT 

What does it mean to have a “low” chance vs “high” chance for a chromosomal abnormality?

If the screening test reveals a low chance for the chromosomal abnormality, it is likely your child will not have any of the above conditions. The likelihood of a false negative is incredibly low. According to a scientific literature review of 5,967 high-chance pregnancies, a false negative trisomy happens 0.23% of the time.

What about when the results come back as a high chance for the chromosomal abnormality? According to Catherine Joynson of the Nuffield Council on Bioethics, a high chance doesn’t necessarily mean the child will be born with the condition, either:

“If you receive a high chance result for Down’s syndrome, there is a 1 in 5 (20%) chance that the result is wrong and your fetus does not have the condition. For Patau’s syndrome, there is a 1 in 2 (50%) chance the result is wrong, and for Edwards’ syndrome, it’s a 3 in 5 (60%) chance.” 

The false positive, high-chance result could be due to:

  • The trisomy being in the placenta, not the baby – The cell-free fetal DNA transfers from the placenta into mom’s bloodstream. So, when the trisomy is found in the cff DNA, this usually corresponds with a trisomy in the baby’s DNA. However, sometimes this chromosomal abnormality is confined to the placental tissue DNA—not the baby’s. This is known as placental mosaicism, and it causes about 1% of false positives.
  • A vanishing twin – A vanishing twin is a type of miscarriage where one twin is lost early in pregnancy. If this twin had a chromosomal abnormality, there is a chance that the fetus’s cffDNA is still present in the placenta. This means the positive result is not applicable to the remaining, growing baby. A vanishing twin causes about 0.11% of false positives.

The Third NIPT Result: Inconclusive 

As previously mentioned, the fetal fraction needs to be above 4% for an NIPT to be accurate. This usually occurs around 10-12 weeks but could occur later for some mothers. If the fetal fraction is below 4%, the NIPT will likely fail to provide a result at all. This is because both mom’s and baby’s chromosomes are being included in the analysis; the test cannot separate them. If there’s not enough of the baby’s cffDNA, the screening doesn’t have enough data to identify them via statistical analysis. 

To illustrate: if the test counts 1 million genetic sequences and finds 1.1 million sequences of chromosome 21, the logical conclusion is that the baby must have trisomy 21 (or an extra chromosome 21 in each genetic sequence). However, with a low fetal fraction, this test might result in 1.01 million sequences of chromosome 21, which wouldn’t confidently confirm the appearance of trisomy 21. Instead, this could’ve just been an error in the counting system. 

The 4% marker is the cut-off for when this test result becomes unreliable. Below this, the NIPT returns the result “inconclusive.”

After the NIPT Results: Next Steps 

Because the chromosomal abnormality analysis requires DNA sequencing, it typically takes between 1-2 weeks to return results. Depending on these results, your doctor may have different recommendations:

Low-chance result – With a low-chance result, doctors typically won’t recommend a secondary screening or diagnostic test.

Inconclusive result – When this occurs, your doctor might recommend a follow-up test. It’s possible during the 1-2 weeks you were waiting for the result, the fetal fraction in your blood increased.

High-chance result – Should the result be a high chance of a chromosomal abnormality, your doctor might offer a follow-up diagnostic test called an amniocentesis. Because this poses risks to the baby, however, the test isn’t mandatory.

Amniocentesis: Confirming the Screening Result 

Screenings and diagnostic tests are different in one fundamental way. A screening test offers a probability, not a 100% yes or no answer. A diagnostic test can confirm for sure.

An amniocentesis is an invasive prenatal diagnostic test. The procedure uses a needle to remove amniotic fluid from the uterus, while an ultrasound device monitors the positioning of both the needle and the baby to reduce the risk of injury. The amniotic fluid that surrounds a baby throughout pregnancy contains fetal cells that are shed during development. These cells are isolated and analyzed, offering direct insight into the baby’s chromosomes.

So while an NIPT screens for abnormalities using cffDNA and statistical analysis to create probabilities, amniocentesis goes “straight to the source” of that DNA and provides a diagnosis.

While an amniocentesis does provide an accurate result, the reason it’s not done first is that it is an invasive procedure, meaning there are physical risks to both mom and baby. These risks include: 

  • Leaking amniotic fluid
  • Needle injury to the baby
  • Infection to mom, baby, or both
  • Miscarriage (low risk, 0.1% to 0.3%)

Only about 5-10% of pregnant women opt for an amniocentesis test. This number is low, thanks to the development and accuracy of non-invasive screenings. Even when NIPT screening does come back with a high probability of chromosomal abnormality, parents weigh the risks of the procedure to determine whether it’s worth an invasive test to confirm with a diagnostic.

It’s one more reason why non-invasive tests are so necessary today.

Other Types of NIPT Testing

If you want to know the gender of your baby and you aren’t included in the three indicators that prompt a physician-ordered NIPT, then this is not your go-to test. Not only would this be an expensive option, but if your doctor doesn’t think you need one, then insurance isn’t likely to cover it. This can result in thousands of dollars in hospital bills.

Thankfully, there’s another type of NIPT used specifically for the gender that’s more affordable and accessible.

Early Gender DNA Test 

An NIPT is merely taking a sample of mom’s blood to look for answers within the cffDNA. While a 4% fetal fraction is needed to determine genetic abnormalities, a significantly lower fetal fraction is needed to predict gender. This is what allows the SneakPeek Early Gender DNA Test to be taken as early as 8 weeks into pregnancy, instead of the usual 10-12 weeks. 

How Does the SneakPeek Test Identify your Baby’s Gender?

With SneakPeek, our early gender test uses blood from a small prick of the finger (if you choose an at-home kit). Back at SneakPeek Labs, the blood sample is analyzed for male DNA or Y chromosomes. Since mom wouldn’t have any Y chromosomes in her blood unless she’s carrying a boy, the test only has to detect their presence, rather than run a statistical analysis like other NIPTs. Because of this, less fetal fraction is needed to return a boy or girl result, and the test can be run in 1 day rather than 1 to 2 weeks. That means results are returned quickly!

In sum, the test simply asks: is there, or is there not any Y chromosomes in the blood sample? 

  • If the test detects even a tiny amount of Y chromosomes, the baby is a boy!
  • If no male chromosomes are detected in the blood sample, the baby is a girl!

Using cutting-edge technology, these gender reveal tests are 99.9% accurate as early as 8 weeks pregnant—weeks earlier than a doctor-ordered NIPT test. The best part? You can do this from the comfort of your home and find out baby gender without an ultrasound.

How to Take a SneakPeek Early Gender DNA Test

If you want to discover your baby’s gender and start planning for his or her arrival, SneakPeek offers two ways to perform this test:

  • At-home test – You can collect your blood sample from the comfort of your home with the SneakPeek At-Home Early Gender DNA Test. The gender blood test kit comes with everything you need to take the test and a prepaid return label to send your sample back to SneakPeek Labs. With this method, you’ll learn your baby’s gender within days.
  • Clinical test – If you prefer to have a phlebotomist draw your blood, you can visit a participating  SneakPeek Clinical Early Gender DNA Test location and learn your baby’s gender, also within days.

If you’re ready, you can order your test today and learn whether your little world is a boy or girl sooner than ever before.



NCBI. Non-invasive prenatal testing: use of cell-free fetal DNA in Down syndrome screening.


CDC. Facts about Down Syndrome. https://www.cdc.gov/ncbddd/birthdefects/downsyndrome.html

NIH. Trisomy 18. https://ghr.nlm.nih.gov/condition/trisomy-18

NIH. Trisomy 13. https://ghr.nlm.nih.gov/condition/trisomy-13

Mayo Clinic. Turner syndrome. https://www.mayoclinic.org/diseases-conditions/turner-syndrome/symptoms-causes/syc-20360782

Mayo Clinic. Klinefelter syndrome. https://www.mayoclinic.org/diseases-conditions/klinefelter-syndrome/symptoms-causes/syc-20353949

NCBI. Noninvasive Prenatal Testing: The Future Is Now. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3893900/

Mayo Clinic. Pregnancy after 35: Healthy moms, healthy babies. https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/in-depth/pregnancy/art-20045756

NCBI. False Negative NIPT Results: Risk Figures for Chromosomes 13, 18, and 21 Based on Chorionic Villi Results in 5967 Cases and Literature Review. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4714811/

Nuffield Council on Bioethics. Our concerns about non-invasive prenatal testing (NIPT) in the private healthcare sector. https://www.nuffieldbioethics.org/blog/nipt-private#_ftn2

Mayo Clinic. Amniocentesis. https://www.mayoclinic.org/tests-procedures/amniocentesis/about/pac-20392914

CBS. Prenatal Testing Leads To Unexpected, Staggering Bills For Some Parents. https://dfw.cbslocal.com/2019/08/15/prenatal-testing-leads-to-unexpected-staggering-bills-for-some-parents/

NIH. Y chromosome. https://ghr.nlm.nih.gov/chromosome/Y

Life Labs Genetics. Sample Screening Results Page. https://www.lifelabsgenetics.com/wp-content/uploads/2017/11/Low-Fetal-Fraction-no-zygosity-twins.pdf

SneakPeek aims to provide the most accurate and up-to-date information to help our readers make informed decisions regarding their health before, during, and after pregnancy. This article was written based upon trusted scientific research studies and/or articles. Credible information sources for this article are cited and hyperlinked.

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