What Does NIPT Test For: A Complete Guide

Introduction

Pregnancy is marked by anticipation, excitement, and countless decisions that shape the journey ahead. While most people focus on the woman’s health during the time, understanding the baby’s health early on is equally important. Non-Invasive Prenatal Testing, or NIPT, is a type of genetic test that is changing how expectant parents gain peace of mind. It offers a safe, accurate, and simple way to screen for common chromosomal conditions as early as the first trimester. By analysing a small sample of the mother’s blood, NIPT provides valuable genetic insights without posing any risk to the baby, helping families make more confident, informed choices about their pregnancy care. Let’s learn more about it in this comprehensive blog!

What is NIPT: Understanding the Basics

The Non-Invasive Prenatal Test (NIPT) is an advanced screening test that analyses tiny fragments of foetal DNA circulating in a pregnant woman’s blood. It provides early and accurate detection of several chromosomal abnormalities and genetic conditions.

How Does NIPT Work?

The NIPT test examines cell-free fetal DNA (cfDNA) found in the mother’s bloodstream.

• During pregnancy, fragments of the baby’s DNA pass through the placenta into the maternal circulation.
• The test compares the amount and structure of chromosomal material from the foetus to what is expected, allowing the detection of chromosomal abnormalities such as extra or missing chromosomes.

Unlike amniocentesis or chorionic villus sampling (CVS), NIPT requires only a maternal blood draw, reducing risk to the baby.

What are the Key Advantages of NIPT?

There are several tests, like amniocentesis and CVS, that are done to detect any abnormalities in the fetus. However, NIPT offers several major benefits over traditional prenatal screenings:

• It is non-invasive and safe: A simple blood test poses zero risk of miscarriage, which may occur in amniocentesis or CVS.
• Enables early detection: NIPT can be performed as early as 10 weeks into pregnancy, ahead of anatomical scans.
• Offers exceptional accuracy: Over 99% detection rate for Down syndrome and high rates for other trisomies.
• Gives quick results: Results are usually available within 7–14 days, allowing more time for follow-up if indicated.
• Has lower false positives: NIPT reduces unnecessary anxiety and invasive follow-up procedures compared to older screening methods.

NIPT vs. Traditional Screening Methods

Here’s how the NIPT differs from other traditional screening methods:

Primary Conditions: Chromosomal Abnormalities Detected Using NIPT

One of the primary uses of NIPT is to detect common chromosomal abnormalities.

Trisomy 21 (Down Syndrome)

• Caused by an extra copy of chromosome 21.
• The most common chromosomal disorder, which affects 1 in 700 births.
• Causes intellectual disability, characteristic facial features, and health problems
• NIPT shows a 99% detection rate for Trisomy 21.

Trisomy 18 (Edwards Syndrome)

• Caused by an extra copy of chromosome 18.
• Results in severe developmental issues and multi-organ effects.
• NIPT shows a 97% detection rate.

Trisomy 13 (Patau Syndrome)

• Occurs due to an additional chromosome 13.
• Causes significant disability and structural anomalies.
• NIPT detection rate is >90%.

Why are They the Primary Targets?

These three conditions are the primary targets for NIPT because they occur more commonly than other viable trisomies and are known to cause significant health problems.

Sex Chromosome Abnormalities

In addition to trisomies, NIPT is effective for diagnosing sex chromosome abnormalities.

What NIPT Can Detect?

• Turner Syndrome (Monosomy X): Occurs due to a missing X chromosome in females—results in short stature, infertility, and heart/kidney issues.
• Klinefelter Syndrome (47, XXY): Caused by an extra X chromosome in males; characterised by mild symptoms, infertility, and educational challenges.
• Triple X Syndrome (47, XXX) and (47, XYY) Syndrome: Usually mild presentations, especially tall stature and learning difficulties.

Detection rates for these syndromes range from 90% to 95% using NIPT. However, the test’s predictive value for these sex chromosome abnormalities is slightly lower than that for trisomies.

Additional Capabilities of NIPT

NIPT is also very useful in determining the following:

• Foetal Sex Determination: NIPT reveals the baby’s gender as early as 10 weeks into pregnancy with 99% accuracy. This is helpful for families with a risk of X-linked disease.
• Rh Blood Type (RhD Status): Some NIPT panels detect if the foetus is Rh positive or negative—relevant for Rh-negative mothers to prevent haemolytic disease. An NIPT test acts as a guide for RhIg therapy (anti-D immunoglobulin).
• Microdeletion Syndromes: Expanded NIPT panels can detect some microdeletion syndromes, but with variable detection rates. These typically include 22q11.2 deletion syndrome (DiGeorge syndrome), 1p36, Angelman, Prader-Willi and Cri-du-chat syndromes.

Testing for these is less sensitive than testing for trisomies and may result in higher false-positive rates, and always requires diagnostic confirmation.

When Can NIPT Be Performed?

The NIPT genetic test can be performed as early as 10 weeks of pregnancy, with some labs allowing testing as early as 9 weeks. There is no upper limit, and it can be performed any time during pregnancy, unlike amniocentesis (15–20 weeks) or CVS (10–13 weeks). The NIPT test requires a single blood draw from the mother’s arm, with no special preparation required.

Factors affecting test success:

• Sufficient foetal DNA
• Optimal maternal weight
• Multifetal pregnancies can reduce fetal fraction and delay reliable testing.

Results are typically ready in 7–14 days, sometimes as quickly as 3–4 working days.

Who Should Consider NIPT?

NIPT is available to all pregnant women, regardless of age or risk factors, and is increasingly used as the first-line non-invasive screening method worldwide.

The NIPT is particularly recommended for:

• Advanced maternal age (35+ years)
• Previous chromosomal abnormality in pregnancy
• Soft markers on ultrasound or an abnormal first-trimester screen
• Family history of genetic conditions, IVF conception, parental anxiety
• Multiple pregnancies, egg or embryo donation, surrogacy, or higher maternal BMI.

Doctors may highly recommend NIPT in the following clinical scenarios:

• Twin pregnancies
• Egg donor pregnancies
• Surrogate pregnancies
• High maternal BMI

Understanding NIPT Results

After undergoing an NIPT, most couples are anxious about interpreting and understanding the results. While it is recommended to get a consultation with your doctor or a genetic counsellor, here’s a quick guide to help you understand your NIPT results:

• Negative (Low Risk) Result
  • The vast majority of tests (>95%) return a negative result, indicating no evidence of the tested chromosomal abnormalities.
  • Provides substantial reassurance but not absolute certainty.

• Positive (High Risk) Result
  • Indicates an increased risk for specific genetic abnormalities.
  • A positive result is NOT diagnostic but requires confirmation via amniocentesis or CVS.
  • Genetic counselling is highly recommended for all positive outcomes.

• Test Failure or “No Result”
  • Occurs in 1–5% of cases, usually due to low fetal fraction.
  • Most commonly resolved with a repeat blood draw, especially once gestational age increases.

What is the foetal fraction?

This is the percentage of foetal DNA in maternal blood.

• A minimum threshold is required.
• Higher maternal BMI or early gestation lowers the odds of test success.

How Accurate is NIPT? Does it Have Limitations?

The NIPT has a high detection rate for trisomies and sex chromosome disorders – >99% for Down syndrome, >97% for Edwards syndrome, >90% for Patau syndrome; 90–95% for sex chromosome disorders.

At the same time, false positives are very low for trisomies (<0.1%) and higher for sex chromosomes (up to 1%).

Limitations of the NIPT

• It is a screening test and not a diagnostic one.
• Certain disorders like neural tube defects, heart defects, and single-gene diseases require separate tests or an ultrasound and cannot be detected using NIPT.
• Sometimes, placental mosaicism or maternal health conditions can lead to false-positive or false-negative results.

What NIPT Does NOT Test For?

The NIPT does not diagnose the following conditions:

• Neural tube defects: These typically require ultrasound or AFP testing.
• Structural congenital disabilities (heart defects, cleft lip, etc.)
• Single-gene disorders (unless specifically ordered)
• Open abdominal wall defects
• All possible genetic conditions

How Does Laboratory Quality Affect NIPT Results?

Quality and standard protocols matter and affect NIPT reliability.

• Opting for accredited laboratories certified to ISO, GMP, CAP/CLIA, and advanced NGS platforms improves the accuracy of test results.
• Whole genome or targeted sequencing approaches used by labs like FSG, with expert geneticists interpreting results, ensure reliable results.
• State-of-the-art certified labs offer comprehensive reporting and access to genetic counselling, which are hallmarks of high-quality care.

Takeaway: Why NIPT Is a Powerful Screening Tool

NIPT is one of the most advanced and accurate non-invasive prenatal screening tests for common chromosomal disorders, providing families with reliable, early genetic information that empowers them to make informed decisions throughout pregnancy. Even though NIPT is just a screening test, it reduces the need for invasive diagnostic tests. Always confirm positive findings and consult genetic specialists for interpretation, choosing quality-accredited labs for testing.

Need a NIPT? Book now at FSG Labs!

Frequently Asked Questions 

1. What does the NIPT test for?

NIPT tests for trisomy 21, 18, 13, sex chromosome abnormalities, foetal sex, RhD status, and select microdeletions.

2. When can NIPT be done?

This test can be done as early as 10 weeks of pregnancy.

3. How accurate is NIPT?

The NIPT is highly accurate in predicting trisomies, with 90–99% accuracy, and in detecting sex chromosome abnormalities, with 90% to 95% accuracy.

4. Is NIPT a diagnostic test?

No, NIPT is only a screening test. Confirmed diagnosis requires amniocentesis or CVS.

5. Can NIPT detect all genetic disorders?

No. The NIPT cannot detect some conditions, such as neural tube defects, structural defects, or single-gene diseases, which require separate tests.

6. Can NIPT determine a baby’s gender?

The NIPT can detect the foetal gender with over 99% accuracy from 10 weeks.

7. Is NIPT safe?

NIPT is completely safe with no miscarriage risk.

8. Can NIPT be done with twins?

Yes, but its accuracy is slightly reduced.

9. What is foetal fraction?

It is the percentage of foetal DNA in maternal blood and a critical factor for NIPT success.

10. How long does it take for NIPT results?

It takes around
7–14 days after sample collection.

11. Does NIPT replace ultrasound?

No, ultrasound is vital for structural assessment.