A NIPT is a type of blood test you can take if you’re pregnant to determine the sex of the baby and whether it might develop a genetic disorder, such as Down syndrome.
A noninvasive prenatal test (NIPT) measures tiny pieces of cell-free DNA (cfDNA) from the placenta that are present in a pregnant person’s blood. cfDNA is created when these cells die and are broken down, releasing some DNA into the bloodstream.
The NIPT is commonly referred to as the noninvasive prenatal screening (NIPS). It’s done around the 10th week of pregnancy, after sufficient cfDNA has entered the fetus.
Most commonly, the test is used to determine the baby’s sex and whether it has any genetic irregularities that could increase the risk of developing genetic disorders.
It’s important to note, however, that NIPT is a screening test, not a diagnostic test. It can’t diagnose a genetic condition with certainty, but it could predict whether the risk of a genetic condition is high or low.
Keep reading to learn more about what conditions the NIPT may help identify, how it’s done, and the possible risks of getting it done.
NIPT assesses for conditions caused by having an extra or missing copy of a specific chromosome. This is a DNA molecule in which the information of a specific cell is structured and stored.
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NIPT most commonly assesses for three conditions, including:
- Down syndrome (trisomy 21 [T21])
- Edwards syndrome (trisomy 18 [T18])
- Patau syndrome (trisomy 13 [T13])
NIPT can also look at the sex chromosomes, X and Y, to indicate whether you may be carrying a male or female baby.
The NIPT is a noninvasive blood test, which means it poses no risks to you or the baby. The test is usually performed at a doctor’s office with an OB-GYN, midwife, or primary care physician.
To perform the test, a healthcare professional will draw blood from the person carrying the baby. Once the blood is drawn, it will be sent to a specialized lab, where technicians will analyze the results.
The results will be sent back to the doctor’s office within around 10 days of the blood draw. Each office may have a different policy for delivering results, but someone will likely contact you and provide guidance from there.
If you don’t want to know the sex of the baby before giving birth, it’s important to tell the person during your blood draw appointment so they can mark this down in your file.
The NIPT is not a mandatory examination, which means you aren’t required to undergo it. There are several ethical, financial, and moral reasons why people choose to get or not get a NIPT.
For instance, some people choose not to get a NIPT because it’s too expensive or feels unethical, while others get it done because it can help them prepare for possibly giving birth to and raising a child with a disability.
According to the American College of Obstetricians and Gynecologists, every pregnant person should be given the opportunity to have screening and diagnostic tests, such as an NIPT, regardless of their age or the risk of the baby having a chromosomal irregularity.
In some cases, however, you may not be able to get an NPIT if:
- you have cancer
- you have a chromosomal condition or have had a balanced chromosomal translocation
- you’ve had an organ transplant, stem cell therapy, or a blood transfusion within 4 months
- you’re carrying three babies or more
Deciding to have an NIPT is a personal decision, so it’s OK to take the time you need to determine what’s best for you.
If you’re in the first trimester (1 to 3 months) of your pregnancy, consider consulting an OB-GYN or midwife. They can provide you with the resources and support you need during your pregnancy, which can help you make decisions like whether to get an NIPT.
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Your healthcare team may comprise several people who can provide support.
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The NIPT measures the fetal cfDNA in the birthing person’s bloodstream, which comes from the placenta. This is called the fetal fraction.
For the most accurate test results possible, the fetal fraction must be over 4%. This usually happens around the 10th week of pregnancy, which is why the test is recommended after this time.
There are several ways the fetal cfDNA can be analyzed.
The most common way is to determine the amount of both maternal and fetal cfDNA. The test will look at specific chromosomes to see if the percentage of cfDNA from each of these chromosomes is considered “normal.”
If it falls within the standard range, the result will be “negative.” This means the fetus has a decreased risk of the genetic conditions caused by the chromosomes in question.
If the cfDNA level exceeds the standard range, this could lead to a “positive” result, indicating that the fetus may have an increased risk of a genetic condition.
However, it’s important to remember that the NIPT isn’t 100% conclusive. Positive results require further testing to confirm any true-positive fetal chromosomal irregularity or related disorder.
In rare cases, it’s possible to have a false-positive or false-negative NIPT result. For a false-negative result, the baby may be born with a genetic irregularity that was not detected with the NIPT or additional screenings throughout the course of pregnancy.
The authors of a 2022 review found that NIPT had a very high sensitivity (true positive rate) and specificity (true negative rate) for the detection of T21, T18, and T13 chromosomal conditions.
In single-child births, the detection rates for NIPT were:
- T21: 99%
- T18: over 96%
- T13: over 90%
Remember, NIPT is not 100% accurate and cannot be used to diagnose a condition. In rare cases, it’s possible to have false-positive or false-negative results. This may be due to:
- low fetal levels of cfDNA
- vanishing twin
- birthing person chromosome irregularity
- other genetic irregularities within the fetus
In a 2021 study in 56,545 pregnant people who underwent NIPT, 54 test results were false-positive (0.95%) and 3 test results were false-negative (0.006%).
A healthcare professional can help you better understand your test results and determine any next steps, such as additional genetic testing.
If your NIPT results are positive, a healthcare professional will most likely recommend additional testing to confirm the results. These may include:
These two tests can determine if the fetus has any chromosomal abnormalities with more diagnostic certainty, but it’s important to note they’re more invasive and increase the risk of pregnancy loss.
They’re recommended selectively and cautiously based on the collaborative decision between you and your medical team.
That said, there are additional noninvasive screenings that might be suggested, including:
- first trimester risk assessment, usually done at 11 to 14 weeks
- quad screening, usually at 15 to 20 weeks
- fetal structural survey, usually at 18 to 22 weeks
A doctor can help develop the best course of action for you.
The NIPT prenatal test is an elective screening tool used to assess the genetic risk of a fetal chromosomal irregularity, such as Down syndrome, in the first trimester of pregnancy.
A healthcare professional may recommend the NIPT test if you have any risk factors for developing these genetic disorders.
While the test could help you better prepare for giving birth to and raising a child with a possible disability, it’s important to note that you don’t have to take it, and it’s not 100% accurate.
The NIPT is a personal choice, and it can have a profound emotional impact on anyone considering the test. If you have any questions or concerns about the NIPT screen, speak with a healthcare professional for guidance and support.