NIPT in Pregnancy: What It Detects, When to Take It, Accuracy & What Happens After a High-Risk Result

If you have been offered an NIPT during pregnancy, it is quite normal to have questions before deciding whether to take it.

What exactly does the test look for? Is it safe for the baby? How early can it be done? If the result says “high risk,” does that mean the baby definitely has a genetic condition?

The short answer is that NIPT is a screening test, not a diagnostic test. It analyses small fragments of placental DNA found in the mother's blood and estimates the chance of certain chromosome conditions in the pregnancy. It is particularly useful for screening for trisomy 21 (Down syndrome), trisomy 18 and trisomy 13. Current professional guidance considers cell-free DNA screening to be the most sensitive and specific screening method for these common fetal aneuploidies.

NIPT can generally be performed from 10 weeks of pregnancy. A low-risk result substantially reduces the chance of the conditions being screened for, but does not eliminate it. A high-risk result needs further assessment and, when confirmation is required, diagnostic testing such as chorionic villus sampling (CVS) or amniocentesis.

That distinction matters. A blood test can estimate risk; it cannot, by itself, establish a diagnosis.

What is NIPT in pregnancy?

NIPT stands for Non-Invasive Prenatal Testing.

It is also commonly called:

• Cell-free DNA screening
• cfDNA screening
• NIPT test
• Non-invasive prenatal screening

During pregnancy, fragments of DNA from the placenta circulate in the mother's bloodstream. A blood sample taken from the mother can therefore provide information about the chromosome pattern associated with the pregnancy.

The test does not require a needle to enter the uterus. It is performed using a maternal blood sample.

That is one reason NIPT has become an important option in prenatal screening.

However, the name can sometimes create confusion. “Non-invasive” refers to how the sample is collected. It does not mean that NIPT provides a definitive diagnosis.

When can NIPT be done?

NIPT can generally be performed from 10 weeks of pregnancy.

Testing earlier than the recommended gestational age may result in an insufficient amount of placental DNA being available for analysis.

The exact timing can depend on the laboratory, pregnancy circumstances and the type of test being offered. Before testing, it is useful to confirm:

• How many weeks pregnant you are
• What conditions the laboratory screens for
• Whether the pregnancy is a singleton or multiple pregnancy
• What happens if the result is inconclusive
• Whether genetic counselling is recommended
• What follow-up testing would be available if the result is high risk

NIPT is therefore not simply a matter of having a blood sample taken. Understanding what the particular test covers is an important part of the decision.

What does NIPT detect?

The main purpose of NIPT is screening for certain fetal chromosome conditions.

The most established targets are:

Trisomy 21, down syndrome

Trisomy 21 occurs when there is an additional copy of chromosome 21.

NIPT is particularly effective at screening for trisomy 21 and is considered the most sensitive and specific screening test for this common aneuploidy.

Trisomy 18, edwards syndrome

Trisomy 18 is associated with significant fetal abnormalities and can affect multiple organ systems.

NIPT can screen for an increased chance of trisomy 18.

Trisomy 13, patau syndrome

Trisomy 13 is another chromosomal condition that can cause significant fetal abnormalities.

NIPT can also screen for an increased chance of trisomy 13.

Sex chromosome conditions

Some NIPT panels also offer screening for differences involving the sex chromosomes.

This part of testing is somewhat different from screening for trisomies 21, 18 and 13. Current SMFM guidance recommends that sex chromosome aneuploidy screening be offered as an opt-in after appropriate pre-test counselling.

Whether this information is included, and which conditions are covered, depends on the specific test.

Does NIPT detect every genetic condition?

No.

This is one of the most important limitations to understand before having NIPT.

NIPT is designed to screen for particular chromosome conditions. It does not screen for every genetic disease, every chromosome abnormality or every fetal structural problem.

For example, NIPT does not replace:

• The first-trimester ultrasound
• The NT assessment when indicated
• The detailed anomaly scan
• Fetal echocardiography when recommended
• Diagnostic genetic testing
• Evaluation of fetal growth and anatomy

Some laboratories also offer screening for rare microdeletions or other uncommon genetic conditions. Routine population screening for microdeletion conditions using cfDNA is not recommended by SMFM. When a patient wants definitive information about fetal copy-number variants, diagnostic testing may be more appropriate.

This is why choosing an NIPT should involve understanding exactly what is being tested rather than simply looking at the number of conditions included on a laboratory package.

How does NIPT work?

The placenta releases small fragments of DNA into the mother's bloodstream. These fragments are commonly referred to as cell-free DNA.

A blood sample is collected from the mother and sent to the laboratory.

The laboratory analyses the available DNA fragments and looks for patterns associated with an increased or decreased likelihood of particular chromosomal conditions.

The important point is that the DNA being analysed is largely derived from the placenta.

Because the placenta and fetus generally have the same genetic makeup, the test can provide useful information about the pregnancy.

But they are not always genetically identical.

Conditions such as placental mosaicism can sometimes affect the result. Other circumstances can also lead to a false-positive, false-negative or non-reportable result.

That is one reason NIPT remains a screening test.

Is NIPT a diagnostic test?

No. NIPT is a screening test.

This distinction should be clear before interpreting the report.

A screening test estimates the probability that a particular condition is present.

A diagnostic test attempts to establish whether the condition is actually present.

For prenatal diagnosis, procedures such as:

• Chorionic villus sampling (CVS)
• Amniocentesis

may be used when clinically appropriate.

Therefore:

Low-risk NIPT ≠ complete guarantee that the baby is unaffected.

High-risk NIPT ≠ confirmed diagnosis.

The result has to be interpreted together with the pregnancy history, ultrasound findings and, where appropriate, diagnostic testing.

How accurate is NIPT?

There is no single accuracy percentage that can accurately describe every NIPT result.

The performance of the test varies according to:

• The chromosome condition being screened for
• The test methodology
• The pregnancy type
• The underlying likelihood of the condition
• The fetal fraction
• Maternal and placental factors
• Whether the pregnancy is singleton or twin
• The particular laboratory and assay being used

For common fetal aneuploidies such as trisomy 21, 18 and 13, professional guidance considers cfDNA to be the most sensitive and specific screening approach currently available.

But “highly accurate” does not mean “diagnostic.”

This is especially important when interpreting a positive or high-risk result.

A test can have excellent sensitivity and specificity and still produce false-positive results, particularly when the condition being screened for is uncommon in the individual pregnancy.

That is why the positive predictive value, or PPV, also matters.

What is positive predictive value?

Positive predictive value refers to the likelihood that a person with a positive screening result actually has the condition being screened for.

This depends partly on the underlying probability of the condition.

For example, two women could receive the same type of high-risk screening result, but the chance that the result represents a true fetal condition may not be identical because their baseline risks and clinical circumstances may differ.

This is one reason it is better not to interpret an NIPT report using a generic statement such as:

“NIPT is 99% accurate, so a high-risk result means the baby has the condition.”

That interpretation is incorrect.

The actual report needs to be reviewed in context.

What does a low-Risk NIPT result mean?

A low-risk result means that the screening test found a lower likelihood of the chromosome conditions included in the test.

This can provide considerable reassurance.

However, it does not mean that every possible genetic condition has been excluded.

Nor does it replace ultrasound assessment.

A pregnancy with a low-risk NIPT result still requires appropriate routine antenatal care and ultrasound evaluation.

If a later ultrasound identifies a structural abnormality, the pregnancy may need further assessment despite an earlier low-risk NIPT.

In other words:

NIPT answers one question. It does not answer every question about fetal health.

What does a high-Risk NIPT result mean?

A high-risk result means that the screening test has identified an increased likelihood of a particular chromosome condition.

It does not mean that the diagnosis is confirmed.

This is an important moment, and the next step should generally be a proper review rather than an immediate decision based only on the laboratory report.

A high-risk result may sometimes occur because of factors other than an affected fetus. These can include biological differences between placental and fetal DNA and other maternal or pregnancy-related factors.

SMFM recommends appropriate counselling following high-risk cfDNA results, and diagnostic confirmation should be considered when definitive information is needed.

What happens after a high-Risk NIPT result?

Receiving a high-risk result can be frightening, especially if the report is read without clinical explanation.

The next step is usually not to assume the diagnosis.

A fetal medicine specialist or an appropriately trained clinician may review several pieces of information together.

The NIPT report is reviewed

The exact chromosome finding, test methodology and laboratory report should be examined.

Not every “high-risk” result has the same clinical meaning.

Your pregnancy history is considered

Your age, gestational age, pregnancy type, previous screening and other relevant factors may influence interpretation.

Ultrasound findings are reviewed

Ultrasound can provide additional information about fetal anatomy and may identify findings that alter the overall assessment.

However, a normal ultrasound does not necessarily rule out a chromosome condition.

Genetic counselling may be recommended

Genetic counselling can help explain:

• What the result actually means
• The difference between screening and diagnosis
• Possible explanations for the result
• Available diagnostic options
• The potential benefits and limitations of further testing

Diagnostic testing may be offered

If definitive information is required, CVS or amniocentesis may be discussed.

These tests obtain fetal/placental material directly for chromosome analysis and are diagnostic procedures rather than screening tests.

Decisions can then be made with better information

The purpose of this process is to avoid making major pregnancy decisions based solely on a screening result.

Can you have CVS or amniocentesis after a high-Risk NIPT?

Yes.

A high-risk NIPT may be one of the reasons diagnostic testing is offered.

The choice between CVS and amniocentesis depends on factors such as:

• Gestational age
• The suspected condition
• Ultrasound findings
• Clinical circumstances
• Availability of testing
• The patient's preferences

Your fetal medicine specialist can explain the potential benefits and risks of each procedure.

The important principle is that NIPT should not be treated as a substitute for diagnostic confirmation when confirmation is required.

Should pregnancy decisions be made from NIPT alone?

A high-risk NIPT should not automatically be treated as proof of a fetal diagnosis.

This is particularly important when a decision would have major or irreversible consequences.

Professional guidance emphasizes the distinction between screening and diagnostic testing. A positive cfDNA result should be followed by appropriate counselling and diagnostic testing when confirmation is needed.

The goal is not to create unnecessary anxiety. It is to make sure that important decisions are based on the strongest information reasonably available.

NIPT vs NT scan: are they the same?

No.

NIPT and NT assessment provide different types of information.

These tests should not automatically be viewed as competitors.

In many pregnancies, ultrasound remains an essential part of care even when NIPT has been performed.

NIPT vs double marker test

The Double Marker Test is part of conventional first-trimester screening and uses maternal blood markers together with ultrasound and other clinical information.

NIPT uses cell-free DNA to screen specifically for certain chromosomal conditions.

The two approaches are therefore based on different biological information.

Current professional guidance considers cfDNA the most sensitive and specific screening test for the common fetal aneuploidies.

However, choosing a screening strategy is not simply about asking which test is “better.” Cost, availability, gestational age, pregnancy type, previous testing, ultrasound findings and personal preferences can all matter.

A fetal medicine consultation can help determine which approach is appropriate for an individual pregnancy.

Is NIPT recommended after IVF?

Pregnancies conceived through IVF can also be offered prenatal genetic screening and diagnostic testing.

Importantly, having undergone preimplantation genetic testing does not automatically eliminate the need to discuss prenatal screening or diagnostic testing during pregnancy.

SMFM recommends that patients who have achieved pregnancy through IVF be offered options for prenatal genetic screening and diagnostic testing, even when preimplantation genetic testing has been performed.

The appropriate approach depends on the type of preimplantation testing performed and the circumstances of the pregnancy.

Is NIPT reliable in twin pregnancy?

NIPT can be used in twin pregnancies, but interpretation is different from that in singleton pregnancies.

Current SMFM guidance recommends cfDNA as a first-line screening option for trisomy 21 in twin pregnancies. Screening for trisomy 18 and trisomy 13 is also recommended, although the number of affected twin pregnancies available for study is more limited.

Some forms of cfDNA screening are not recommended in higher-order multiple pregnancies because evidence is insufficient.

Twin pregnancies also introduce additional considerations, including:

• Chorionicity
• Fetal fraction
• Vanishing twin
• Fetal demise
• Differences between the two fetuses
• Ultrasound findings

For this reason, a twin pregnancy should not simply be treated as a singleton pregnancy with “two babies.”

What if NIPT gives an inconclusive or no-Result report?

Sometimes the laboratory cannot provide a reportable result.

This may be described as:

• No result
• Non-reportable
• Inconclusive
• Insufficient fetal fraction

There are several possible reasons.

The test may have been performed too early, there may not have been enough placental DNA in the sample, or maternal and pregnancy-related factors may have affected the result.

A non-reportable result should not simply be ignored.

SMFM's updated guidance specifically addresses the management of inconclusive cfDNA results and recommends appropriate counselling and further evaluation.

Depending on the circumstances, your doctor may discuss repeat screening, ultrasound assessment or diagnostic testing.

Does NIPT replace the anomaly scan?

No.

This is one of the most common misconceptions about NIPT.

NIPT mainly provides information about selected chromosome conditions.

The anomaly scan evaluates fetal anatomy.

A detailed ultrasound can assess structures such as:

• Brain
• Face
• Spine
• Heart
• Stomach
• Kidneys
• Bladder
• Limbs
• Abdominal wall
• Placenta
• Umbilical cord

A fetus can have a structural abnormality even when NIPT indicates a low risk for the chromosome conditions being screened.

For this reason, prenatal genetic screening and fetal anatomical assessment serve different purposes.

What conditions can NIPT miss?

NIPT can miss or does not evaluate many conditions.

Depending on the test, this may include:

• Structural birth defects
• Many single-gene disorders
• Some chromosome abnormalities
• Some genetic syndromes
• Conditions unrelated to the chromosomes being screened
• Problems that develop later in pregnancy
• Certain fetal anatomical abnormalities

A low-risk NIPT therefore should never be interpreted as a general statement that the fetus is completely healthy.

It means the likelihood of the specific conditions screened by that test is reduced.

Who should consider NIPT?

NIPT can be discussed with pregnant patients as part of prenatal genetic screening.

Current guidance recommends that screening for common aneuploidies be routinely available to obstetrical patients.

A discussion about NIPT may be particularly useful when:

• You want early screening for common chromosomal conditions
• You have questions about Down syndrome screening
• You have had an abnormal or borderline screening result
• You have a pregnancy conceived through IVF
• You are carrying twins
• An ultrasound has raised a question requiring further assessment
• You want to understand the available prenatal screening options

The decision to undergo screening remains a personal one.

What should you ask before taking an NIPT?

Before giving a blood sample, consider asking:

What exactly does this test screen for?

Different laboratories offer different panels.

From how many weeks can I take the test?

Most standard cfDNA screening begins from around 10 weeks.

Is my pregnancy suitable for this test?

Singleton and multiple pregnancies may require different considerations.

What happens if my result is high risk?

Ask where you would receive counselling and whether diagnostic testing is available.

What happens if the test gives no result?

This is worth discussing before testing rather than after receiving an inconclusive report.

Does the test screen for rare conditions?

If it does, ask what evidence supports those additional findings and how they would be followed up.

Will I still need ultrasound scans?

Yes. NIPT does not replace routine fetal ultrasound or the anomaly scan.

When should you speak to a fetal medicine specialist?

A fetal medicine consultation can be particularly useful if:

• Your NIPT result is high risk
• Your NIPT result is inconclusive
• An ultrasound shows an unexpected finding
• You are carrying twins or a higher-order multiple pregnancy
• You have conceived through IVF
• You have a previous pregnancy affected by a chromosome condition
• You have a family history of a genetic condition
• You are uncertain which prenatal screening option to choose
• You are considering CVS or amniocentesis

The value of specialist counselling is not limited to interpreting a report. It is about putting the result into the context of the whole pregnancy.

NIPT in trichy: why specialist interpretation matters

For women seeking fetal medicine care in Trichy, prenatal screening should be approached as part of the wider pregnancy assessment rather than as an isolated laboratory test.

At Trichy Fetal Medicine & Fertility Centre, fetal medicine services include Down syndrome screening, NIPT, anomaly scanning, genetic counselling, fetal echocardiography, second-opinion scans and other specialised prenatal procedures.

When a screening result raises concern, the next step may involve a combination of ultrasound assessment, counselling and, when appropriate, diagnostic testing.

The centre's listed services include procedures such as amniocentesis and CVS, which may be considered when definitive prenatal diagnosis is required.

NIPT test cost: why prices can differ

Patients often search for “NIPT test cost” before deciding where to have the test.

However, there is no single universal price.

The cost can vary depending on:

• Laboratory
• Test methodology
• Number of conditions included
• Whether sex chromosome screening is included
• Whether additional conditions are screened
• Collection and processing arrangements
• Genetic counselling or consultation
• Whether additional testing is required afterward

A cheaper test is not necessarily equivalent to another test with a broader panel.

Before comparing prices, compare what the test actually covers.

What is the most important thing to remember about NIPT?

NIPT is a powerful prenatal screening tool, but it is still a screening test.

Think of the process in three steps:

NIPT → estimates risk

Diagnostic testing → confirms or excludes certain conditions

Ultrasound → evaluates fetal development and anatomy

These are complementary parts of prenatal care rather than interchangeable tests.

A low-risk NIPT result can be reassuring, but routine pregnancy care and ultrasound remain important.

A high-risk NIPT result needs careful interpretation and, when appropriate, diagnostic confirmation.

And if the result is inconclusive, that also deserves proper medical follow-up rather than simply being treated as a failed test.

NIPT has changed the way many chromosome conditions are screened for during pregnancy. It offers an early, non-invasive way of assessing the likelihood of certain chromosomal conditions, particularly Down syndrome.

But the value of the test lies not just in the blood sample or the number printed on the report.

The interpretation matters just as much.

A low-risk result needs to be understood in the context of the rest of the pregnancy. A high-risk result needs careful counselling and, when appropriate, diagnostic confirmation. An inconclusive result also deserves proper follow-up.

If you are considering NIPT, or have already received a result that you are unsure how to interpret, discussing it with a fetal medicine specialist can help you understand what the result means and what options are available next.

You can read about how we run the NIPT at our centre, and who performs it, on the team page.

Related guides

• NIPT vs NT Scan vs Double Marker Test: Key Differences
• What Does a High-Risk NIPT Result Mean?
• Can NIPT Detect Down Syndrome?
• NIPT in Twin Pregnancy: Is It Reliable?
• What Happens After a Positive NIPT Result?