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What is noninvasive prenatal testing (NIPT) and what disorders can it screen for?
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Testing

What is noninvasive prenatal testing (NIPT) and what disorders can it screen for?

Noninvasive prenatal testing (NIPT) analyzes cell-free DNA in a pregnant woman's blood to estimate the risk of fetal chromosomal abnormalities without posing a risk to the fetus.

How NIPT Works

Noninvasive prenatal testing (NIPT), also known as noninvasive prenatal screening (NIPS), analyzes small fragments of DNA circulating in a pregnant woman’s blood. Unlike DNA found in a cell's nucleus, these fragments are free-floating and are called cell-free DNA (cfDNA). These fragments typically arise when cells die and break down, releasing their contents into the bloodstream.

During pregnancy, the mother’s blood contains a mix of cfDNA from her own cells and from the placenta. Because placental cells are shed into the maternal bloodstream and their DNA is usually identical to that of the fetus, analyzing this cfDNA allows for early detection of certain genetic abnormalities without harming the fetus.

What NIPT Screens For

NIPT is primarily used to identify chromosomal disorders caused by an extra or missing copy of a chromosome (aneuploidy). These include:

  • Down syndrome (trisomy 21)
  • Trisomy 18
  • Trisomy 13
  • Extra or missing copies of the X and Y chromosomes (sex chromosomes)

The test may also screen for chromosomal disorders caused by missing (deleted) or copied (duplicated) sections of a chromosome, and it is increasingly being used to test for single-gene disorders.

Understanding Results and Limitations

NIPT is a screening test, not a diagnostic test. It provides an estimate of risk rather than a definitive answer. Results can sometimes indicate an increased risk when the fetus is unaffected (false positive) or a decreased risk when the fetus is actually affected (false negative). Because the test analyzes both maternal and fetal cfDNA, it may also detect genetic conditions in the mother.

The Importance of Fetal Fraction

For the test to be effective, there must be a sufficient amount of fetal cfDNA in the mother’s blood, known as the fetal fraction. This must generally be above 4 percent, which typically occurs around the tenth week of pregnancy. Factors such as testing too early, maternal obesity, sampling errors, or fetal abnormality can lead to low fetal fractions, which may result in an inability to perform the test or a false negative result.

Interpreting the Data

The most common method for determining chromosomal aneuploidy involves counting all cfDNA fragments. If the percentage of fragments from a specific chromosome is higher than expected, it indicates an increased likelihood of a trisomy condition (a positive result). A positive screening result indicates that further diagnostic testing should be performed to confirm the findings.

Frequently Asked Questions

NIPT is typically recommended to be performed after the 10th week of pregnancy. Performing it earlier than this may result in insufficient levels of fetal cell-free DNA in the maternal blood, leading to a "no-call" or inconclusive result. Certain conditions can affect accuracy, including twin pregnancies, which are generally not suitable for standard NIPT, and maternal conditions such as a recent organ transplant, cancer, or blood disorders that may introduce non-fetal DNA into the bloodstream. :: If my NIPT result shows an increased risk for a chromosomal abnormality, does that mean my baby definitely has the condition?::No, an increased risk result from NIPT is not a diagnosis. It indicates a higher statistical probability that the fetus has a specific chromosomal abnormality, but false positives can occur. To confirm or rule out the condition, your healthcare provider will recommend diagnostic testing, such as chorionic villus sampling (CVS) or amniocentesis, which directly analyzes fetal cells. :: Can NIPT detect all genetic disorders, or is it limited to specific chromosomal issues?::Standard NIPT is primarily designed to screen for common aneuploidies, such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13), as well as sex chromosome aneuploidies. While some labs offer expanded panels for microdeletions or single-gene disorders, NIPT cannot detect all genetic conditions. It does not screen for structural birth defects, metabolic disorders, or most single-gene diseases unless specifically included in an expanded panel, and even then, coverage is limited compared to comprehensive genetic testing. :: What happens if the test returns a "no-call" or inconclusive result, and how should I proceed?::A "no-call" result usually means the lab could not detect enough fetal DNA in your blood sample to provide a reliable risk assessment. This does not indicate a problem with the fetus; it is often due to low fetal fraction, which can be influenced by maternal body mass index or the timing of the blood draw. Your provider will likely recommend repeating the blood test in a few weeks or proceeding directly to diagnostic testing like amniocentesis if clinical suspicion remains high.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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