About NIPT (Non-Invasive Prenatal Testing)

Overview

NIPT is a screening method which takes maternal blood and can provide early, safe, and reliable answers about the chromosomal health of a developing baby—minimizing the need for invasive procedures.

The test involves a simple blood test from the pregnant woman to determine whether a pregnancy has certain chromosomal conditions. Non-invasive prenatal tests (NIPT) are safe and pose no risk to mother or baby. It’s recommended that expectant parents take time to learn about the test, its limitations and it is highly recommended to meet and discuss with a healthcare professional before and after the screening process.

An ultrasound scan will be required prior to the blood test to check and date the pregnancy.

Not all non-invasive prenatal screening tests are alike.

Some screening tests require more than one visit to a clinic and multiple blood draws. Results from some of these screening tests are limited to a “risk score” (such as 1 in 500 or 1 in 50) which can be confusing.

In comparison to other screening options, non-invasive prenatal testing provides more reliable results with a higher positive predictive value than traditional serum screens, and do not carry the risk of complications that an invasive procedure can have.

A bit about technology behind the test

All NIPT tests analyse genetic material (DNA) from a pregnant woman’s blood. The methods by which the test is processed in the laboratory vary. Most companies use the latest advances in the next generation sequencing as the instrument and processing method of choice. The world’s market leader in sequencing technology is Illumina and the majority of NIPT tests are processed on Illumina sequencers. This whole genome approach allows more data to be processed which provides better consistency and improved accuracy of the data making for an extremely robust method.

Test options

The test looks for too few or too many copies of chromosomes in the mother and baby, or babies in the case of twins. Missing or extra copies of chromosomes are referred to as “aneuploidies” and may be related to conditions in pregnancy such as Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome), or Trisomy 13 (Patau syndrome).

The test can also look for other conditions caused by missing and extra copies of other types of chromosomes, called sex chromosomes (X and Y). Trisomies occur when three, instead of the usual two, copies of a chromosome are present. Sex chromosome aneuploidies are conditions in which there is a change from the usual 2 copies of sex chromosomes in males (XY) or females (XX). All of these conditions may cause mental or physical disabilities, with different levels of severity.

It is recommended that no irreversible clinical decisions should be made based on these screening results alone. If definitive diagnosis is desired, chorionic villus sampling or amniocentesis would be necessary.

NIPT is currently offered mainly via private clinics to all pregnancies. Also national screening campaigns are slowly starting up in certain countries but these may be limited to certain pregnancies and screening options.