NIPT test or Non-invasive prenatal testing, also known as noninvasive prenatal screening (NIPS), is a technique for estimating the likelihood that a fetus will be born with genetic abnormalities. This test examines tiny DNA fragments circulating in the blood of a pregnant woman. Unlike most DNA, which is located inside the nucleus of a cell, these pieces are free-floating and not contained within cells, earning the name cell-free DNA (cfDNA). These little fragments, which usually include fewer than 200 DNA building blocks (base pairs), form when cells die and their contents, which include DNA, are discharged into the bloodstream.

All through gestation, the mother’s bloodstream contains a mixture of cfDNA from her cells and placental cells. The placenta is uterine tissue that connects the blood supply of the mother to the fetus. During pregnancy, these cells are lost in the mother’s bloodstream. Placental cells typically have DNA that is similar to that of the fetus. The analysis of cfDNA from the placenta allows for the early diagnosis of some genetic disorders without causing harm to the fetus.

The analysis of cfDNA from the placenta enables the early detection of some genetic disorders without harming the fetus. The most common application of NIPT is to screen for chromosomal diseases caused by an extra or missing copy of a chromosome (aneuploidy). Trisomy 21 (due to an extra chromosome 21), trisomy 18 (due to an extra chromosome 18), trisomy 13 (due to an extra chromosome 13), and extra or missing copies are all examples of trisomies. The test’s accuracy varies depending on the disease.

Additional chromosomal diseases caused by missing (deleted) or copied (duplicated) parts of a chromosome may be detected using NIPT. NIPT is now being used to screen for genetic illnesses caused by single-gene variations (variants). Researchers anticipate that as technology advances and the cost of gene testing drops, NIPT will become available for a greater number of hereditary problems.

Why do we need a NIPT?

The NIPT is extremely sensitive, detecting more than 99 percent of patients with Down syndrome. However, it is still a screening test instead of a diagnostic test. This means it can only inform you if you have a higher chance of having a kid with a birth defect, not give you a firm answer.

A diagnostic procedure like chorionic villus sampling (CVS) or amniocentesis is the only way to determine whether your baby has Down syndrome.

The combined first-trimester screening for Down syndrome is available to the majority of women in developed nations. This combines the results of a blood test, the mother’s age, and an ultrasound scan (which measures the thickness of fluid behind the baby’s neck, known as the nuchal translucency) to determine whether the baby is at risk for Down syndrome. The advantage of this form of screening is that it can detect various issues with the pregnancy as well as estimate the fetus’ age.

A NIPT test may be appropriate if:

• Your combined first-trimester screening test indicates that you are more likely to have a baby with Down syndrome.
• Because it was too late or the test wasn’t offered in your location, you didn’t get the combined first-trimester screening test.
• Before you choose diagnostic tests like amniocentesis or CVS, which have a slight chance of miscarriage, make sure you’re at an elevated risk.
• You’re at a higher risk (for example, if you are older  than 35 years or you have had a baby with Down syndrome or other genetic defects)

The NIPT procedure

The NIPT is performed with a simple blood sample of the mother, so you and your baby are not at risk. Your blood will be collected and delivered to a specialized facility, where the results will be analyzed by technicians. Within a few days, your results will be emailed to your OB-GYN or midwife’s clinic. 

Who should undergo a prenatal NIPT test?

The NIPT is usually administered to women depending on the advice and protocols of their OB-GYN or midwife. However, there are specific risks that may cause your physicians to advocate it more strongly.

Some of these risk factors, according to a NIPT review from 2013, are:

• A personal or family history of a pregnancy with a chromosomal abnormality
• The mother’s age is more than or equal to 35
• A chromosomal defect in the mother or father

Must read: Quad Marker For Genetic Defects And Trisomy 18

Understanding the significance of the NIPT test results

The NIPT detects fetal cfDNA in the mother’s bloodstream, which originates in the placenta. This is known as the fetal fraction. The fetal fraction must be greater than 4% for the most accurate test results. This usually occurs around the 10th week of pregnancy, which is why the test is advised after this point.

There are several methods for analyzing fetal cfDNA. The most common method is to calculate the amount of maternal and fetal cfDNA. The test will examine specific chromosomes to determine whether the percentage of cfDNA from each of these chromosomes is “normal.”

If it falls within the normal range, the outcome will be “negative.” This means that the fetus is less likely to develop the genetic conditions caused by the chromosomes in question.

If the cfDNA level exceeds the normal range, this could result in a “positive” result, indicating that the fetus is at an increased risk of a genetic condition. Please be assured, however, that NIPT is not conclusive. Positive results necessitate additional testing to confirm any true-positive fetal chromosomal abnormality or disorder.

We should also mention that the possibility of receiving a false negative NIPT result is extremely low. In this case, a baby might be born with a chromosomal abnormality that was not identified during pregnancy by the NIPT or other screenings.

The Advantages of NIPT

• NIPT is a simple procedure that yields a wealth of information. There are several reasons why it is so popular:
• It is not intrusive. All you need is a simple blood draw during a routine prenatal checkup. There is no need to schedule or devote time to an invasive procedure such as amniocentesis or CVS.
• It is completely safe for you and your baby, with none of the risks associated with other types of testing. (For example, amniocentesis and CVS have a small risk of miscarriage.)
• While additional diagnostic testing is required to confirm results, negative results provide a high degree of accuracy – and reassurance – for a variety of conditions.
• It is available from 9 to 10 weeks of pregnancy or later.
• The results are provided relatively quickly (within a couple of weeks, often sooner).
• If you’re curious, the test can tell you whether you’re expecting a girl or a boy.