Innovations in Prenatal Testing: Non-Invasive Methods for Assessing Foetal Health

When you're expecting a baby, one of the biggest priorities is ensuring the health and well-being of your little one. In the past, prenatal testing often involved invasive procedures that carried a small risk of complications. But thanks to ongoing advances in medical technology, non-invasive prenatal testing (NIPT) methods are now available, providing a safer and more accurate way to assess your baby's health before birth.

As an expectant parent, the idea of invasive testing can be nerve-wracking. After all, you want to do everything possible to protect your unborn child. That's where NIPT comes in – it offers a simple, risk-free solution to gain valuable insights about your baby's development and potential genetic conditions.

What is Non-invasive Prenatal Testing?

NIPT, or the Non-Invasive Prenatal Test, is an accurate screening test used to determine whether your baby is more likely to have genetic health conditions, including Down syndrome and other chromosomal differences. This innovative test can detect certain chromosomal abnormalities, genetic disorders, and other potential issues without any invasive procedures. It requires just a simple blood draw.

Purpose of NIPT

NIPT for analyzing maternal blood can be effective for screening the following conditions.

• Down syndrome (Trisomy 21)
• Edwards syndrome (Trisomy 18)
• Patau syndrome (Trisomy 13)

In certain cases, the chromosomal related syndrome can affect a small percentage of the population and cause intellectual disability and malformations/underdevelopment of various organs of the fetus. It includes,

• DiGeorge syndrome
• 1p36 Deletion syndrome
• Angelman syndrome
• Prader-Willi syndrome
• Cat’s meow syndrome (Cri-du-chat)
• Wolf-Hirschhorn syndrome

Types of Non-Invasive Methods for Assessing Fetal Health

As technology continues to evolve, several types of non-invasive prenatal testing (NIPT) are now available. Let us explore the various types of non-invasive methods to indicate your fetal health.

Cell-Free DNA (cfDNA) Testing

Cell-free DNA consists of short fragments of DNA that are released into the bloodstream. These fragments come from the natural process of cell death (apoptosis) in the body. During pregnancy, cfDNA in the maternal blood includes DNA from both the mother and the fetus. The fetal DNA is derived from the placenta and circulates in the mother's bloodstream.

Cell-free DNA testing analyze the mother's blood sample to screen for common chromosomal abnormalities such as trisomy and numerous alterations of the sex chromosomes. The test can be performed from the tenth week of pregnancy until the 24th week.

Next Generation Sequencing

Genome-wide screenings in NIPT provide information on partial duplications and deletions for all autosomes and aneuploidy status for every chromosome. NIPT's workflow involves several steps, which vary based on the complexity and technical approach. Noninvasive prenatal testing also uses whole-genome next-generation sequencing technology (NGS).

The procedure analyses cfDNA fragments across the whole genome, which is advantageous over other NIPT methodologies. It includes targeted sequences and array-based tests, which identify almost every possible abnormality and might identify some additional genetic diseases.

There are two types of NGS:

• Whole genome sequencing (WGS) analyzes the entire genome, including the exons and introns (coding and noncoding regions). However, the clinical relevance of the method is high and has a complex interpretation of results.
• Whole exome sequencing (WES) only examines the genome's coding regions (exons). It is highly preferred because the exons have greater clinical relevance.

Fetal Cell Assessment

Fetal cells are the DNA fragments derived from the placenta of the fetus that circulate in the blood of pregnant women. The fetal DNA represents up to 10% of the cell-free DNA. The procedure is a simple, convenient, safe, and accurate technique that only requires a blood sample from the fetus.

Despite its high reliability, fetal cell assessment is a screening test and not a diagnostic test. This means that results are usually expressed as probabilities and as positive or high results (presence of chromosomal abnormality). In such cases, it should be corroborated by other invasive tests, such as chorionic villus sampling or amniocentesis.

Non-Invasive Fetal Electrocardiography

Non-Invasive Fetal Electrocardiography (fECG) is an advanced method used to monitor the fetal heart rate and rhythm during pregnancy, primarily in the later stages or during labor and delivery. Unlike standard cardiotocography (CTG), which measures the fetal heart rate and uterine contractions via sensors placed on the mother's abdomen, fECG aims to capture the electrical activity of the fetal heart more directly and with greater detail.

Biophysical Profile (BPP)

A biophysical profile (BPP) is an ultrasound exam that is performed to monitor the movement, body tone and breathing efforts of your baby. Each of these four elements will be given a score of zero to two points, and the scores will move up. If the BPP is performed with an NST and if the NST is ‘reactive’, then an extra two points will be added. For instance,

• A high score of 8 to 10 indicates that the baby is in good condition inside the uterus
• A low score of 0 and 4 usually means that the baby has to be delivered.
• A median score of 6 requires repeated tests within the next 24 hours.

Wrapping Up!

Every pregnancy experience is unique. While you are enjoying the journey, ensure to verify the well-being of your little one, from the first trimester.

At Apollo Diagnostics, we offer various types of non-invasive prenatal testing procedures to screen for different abnormalities in the fetus. Together, we and your healthcare professional help you determine which NIPT test will be best for your pregnancy plan. The ultimate goal of our experts is to reassure every soon-to-be parent that their little one is safe and healthy throughout the exciting journey.

(FAQs)

Q1. What sample will be tested in Non-invasive prenatal testing?

Non-invasive prenatal testing involves the blood sample from the expectant mother. The blood sample is usually sent to a certified laboratory, where the cell-free DNA material is extracted and analyzed. This is because most of the DNA is derived from the mother, while a small amount comes from the fetus's placenta.

Q2. Which is better NIPT or amniocentesis?

NIPT (Non-Invasive Prenatal Testing) holds a significant reputation for providing accurate results for material blood samples with high-risk or low-risk women. On the other hand, experts also recommend performing amniocentesis aligned with NIPT to ensure precise results on the fetus's growth. As amniocentesis is an invasive procedure, usually it is reserved for selected cases.

Q3. What happens if your NIPT test is positive?

If you get a positive result on an NIPT test, your healthcare provider is most likely to order additional diagnostic tests. In certain cases, these diagnostic cases also show negative results, indicating that the fetus doesn't have any kind of chromosomal abnormality condition.