For many parents, the early stages of pregnancy can be a delicate time. A recent clinical review reveals how fragile this period can be, showing that 10-15% of all pregnancies end in miscarriage. What’s even more significant is that a majority of these early losses, nearly half, are linked to fetal chromosomal abnormalities 1.
Among these, autosomal trisomies are the most frequently detected cause. Understanding these risks is the first step toward informed pregnancy care, and modern science has provided us with a powerful tool to do just that.
Non-Invasive Prenatal Testing (NIPT) has revolutionised prenatal screening, offering a highly accurate and risk-free way to detect fetal chromosomal abnormalities early in pregnancy. While NIPT was initially adopted for its ability to detect Down syndrome (Trisomy 21), modern NIPT has evolved to cover a much wider range of genetic conditions.
What is NIPT?
NIPT is a prenatal screening method that analyses fetal DNA circulating in a pregnant mother’s bloodstream. This DNA is believed to come from the placenta and contains genetic information that reflects the fetus’s DNA. Unlike invasive diagnostic tests, which carry a small risk of miscarriage and require sampling amniotic fluid or placental tissue, NIPT is a safe, non-invasive option.
The test typically uses Next-Generation Sequencing (NGS) to count and analyse chromosomal material. The accuracy for common conditions is exceptional, with a sensitivity and specificity exceeding 99.9% for Down syndrome alone. Globally accredited labs like MedGenome combine advanced whole-genome sequencing with proprietary bioinformatics to ensure highly reliable results, validated extensively in Indian populations.
Traditionally, NIPT focused solely on detecting Trisomy 21. However, its scope has now expanded to include a broader range of fetal chromosomal abnormalities and genetic disorders.
What Else Can NIPT Detect?
Trisomy 18 (Edwards Syndrome) & Trisomy 13 (Patau Syndrome)
In addition to Trisomy 21, NIPT reliably screens for Trisomy 18 and Trisomy 13. These chromosomal disorders cause severe congenital disabilities and have high infant mortality rates. Early identification allows families to receive timely counselling and make informed decisions.
Sex Chromosome Aneuploidies (SCAs)
NIPT can also screen for abnormalities involving the X and Y sex chromosomes, known as Sex Chromosome Aneuploidies (SCAs). These include:
- Turner syndrome (XO): Affects females who have only one X chromosome. It can lead to short stature, infertility, and heart defects.
- Klinefelter syndrome (XXX): Affects males who have an extra X chromosome. It is often associated with reduced fertility and learning difficulties.
- Triple X syndrome (XXY): Affects females who have an additional X chromosome. Symptoms are typically mild or non-existent.
- Jacob’s syndrome (XYY): Affects males with an extra Y chromosome, and it can sometimes be linked to tall stature and learning disabilities.
These conditions are often underdiagnosed due to their variable and sometimes mild clinical features, but they can impact an individual’s physical and developmental health. NIPT’s ability to detect SCAs offers crucial insights for early intervention and management.
Rare Autosomal Aneuploidies (RAA)
Non-invasive prenatal testing (NIPT) helps detect Rare Autosomal Aneuploidies (RAA) by performing a genome-wide analysis of cell-free fetal DNA (cffDNA) from the mother’s bloodstream. This allows it to detect both common trisomies (such as those of chromosomes 13, 18, and 21) and Rare Autosomal Aneuploidies (RAA), which are abnormalities involving other non-sex chromosomes.3
When a genome-wide NIPT returns a high-risk result for an RAA, further diagnostic tests, such as karyotyping or chromosomal microarrays, are necessary to confirm the finding. For pregnancies confirmed to be positive for an RAA, close monitoring is recommended. MedGenome has validated NIPT for RAAs, finding that 0.74% of samples were classified as high-risk.
Single Gene Disorders
Some advanced NIPT platforms have started to incorporate the detection of specific single-gene disorders by analysing targeted fetal DNA sequences.5 While this is still an emerging field in clinical practice, it holds promise for non-invasive screening of conditions such as cystic fibrosis, sickle cell anaemia, and Duchenne muscular dystrophy.
Rh Genotyping
NIPT can also determine the fetal Rh blood group (RhD status) from the mother’s blood. This is particularly useful for Rh-negative mothers and helps manage Rh incompatibility, a condition that can lead to hemolytic disease in the fetus if left untreated 6. This allows for the timely administration of anti-D immunoglobulin only when required, avoiding unnecessary treatment.
Limitations
While NIPT is a powerful tool, it’s important to understand its limitations:
- It’s a Screening Test, Not a Diagnostic Test: NIPT results that are positive must be confirmed with diagnostic procedures like amniocentesis or chorionic villus sampling.
- Rare False Positives and Negatives: False positives and negatives can occur in rare cases where the cause can be biological, such as confined placental mosaicism where discrepancies between cfDNA which is known to originate from placental cells, discrepancies from the fetal DNA can sometimes lead to misleading results.
- Single-Gene Disorder Testing Is Still Emerging: This type of testing is not yet widely available and is limited in scope and validation.
- Ethical and Counselling Considerations: Expanded NIPT raises complex ethical questions about which conditions should be screened and how results should be communicated to expectant parents.
Who Should Consider Expanded NIPT?
Expanded NIPT is recommended for:
NIPT can be recommended in all pregnancies irrespective of maternal or gestational age, however pregnant women belonging to categories below should definitely consider,
- Women who have an advanced maternal age, i.e 35 and older. This group has a higher risk of chromosomal abnormalities.
- Pregnant women with abnormal ultrasound findings that suggest a genetic condition.
- Those with high-risk serum screening results who want to clarify their risk and potentially avoid invasive testing.
- Parents with a personal or family history of chromosomal abnormalities.
- Expectant parents who want comprehensive genetic information for reassurance and informed planning.
- Rh-negative mothers who need fetal Rh genotyping to manage incompatibility risks.
Expanded NIPT offers a non-invasive, early, and accurate option for detecting a wide range of fetal genetic abnormalities. It is increasingly becoming a standard part of prenatal care in many countries. Given the complexity of the test results, pre- and post-test genetic counselling is essential as it can help expectant parents fully understand the implications of the results, allowing them to make informed decisions about their pregnancy.
Conclusion
Non-invasive prenatal testing has transformed prenatal care, shifting its focus from a narrow view of Down syndrome to a broad, detailed insight into fetal genetic health. Beyond detecting Trisomy 21, modern NIPT now screens for other common trisomies, sex chromosome aneuploidies, rare autosomal aneuploidies, microdeletions, CNVs, and even some single-gene disorders, all with remarkable accuracy and safety.
While expanded NIPT has its limitations and does not replace diagnostic testing, its growing adoption, driven by advanced sequencing and bioinformatics, is empowering parents and clinicians with crucial early information. As this technology evolves, it promises more personalised, safer, and better-informed pregnancy management worldwide.
For expectant parents considering prenatal testing, understanding the full scope of modern NIPT can help them make the best choices for their pregnancy journey.
References
- Kocaaga, A., & Salik, E. A. (2025). Chromosomal abnormalities of embryos from sporadic and recurrent miscarriages: a tertiary center experience. Molecular Biology Reports, 52(1).
https://pubmed.ncbi.nlm.nih.gov/40439801/ - Non-Invasive Prenatal Testing versus Invasive Procedures: A Meta-Analysis of Diagnostic Performance. (2025). European Journal of Cardiovascular Medicine. https://doi.org/10.5083/ejcm/25-05-17
- Harasim, T., Neuhann, T., Behnecke, A., Stampfer, M., Holinski-Feder, E., & Abicht, A. (2022). Initial Clinical Experience with NIPT for Rare Autosomal Aneuploidies and Large Copy Number Variations. Journal of Clinical Medicine, 11(2), 372. https://doi.org/10.3390/jcm11020372
- Tian, W., Yuan, Y., Yuan, E., Zhang, L., Liu, L., Li, Y., Guo, J., Cui, X., Li, P., & Cui, S. (2023). Evaluation of the clinical utility of extended non-invasive prenatal testing in the detection of chromosomal aneuploidy and microdeletion/microduplication. European Journal of Medical Research, 28(1).
https://pmc.ncbi.nlm.nih.gov/articles/PMC10466692/ - Zhang, H., He, J., Teng, Y., Shi, Q., Liu, F., Peng, C., Linpeng, S., Liu, Y., Zhu, H., Wen, J., Liang, D., Li, Z., & Wu, L. (2025). Non-invasive prenatal testing for dominant single-gene disorders using targeted next-generation sequencing. QJM.
https://pubmed.ncbi.nlm.nih.gov/39982402/ - Yang, H., Llewellyn, A., Walker, R., Harden, M., Saramago, P., Griffin, S., & Simmonds, M. (2019). High-throughput, non-invasive prenatal testing for fetal rhesus D status in RhD-negative women: a systematic review and meta-analysis. BMC Medicine, 17(1).
https://pmc.ncbi.nlm.nih.gov/articles/PMC6375191/
