Humans have 23 pairs of chromosomes (for a total of 46 chromosomes) { One copy of each chromosome comes from the mother (egg); the other copy comes from the father (sperm).

• The first 22 pairs are called autosomes, and they are same in males and females

• The 23rd pair of chromosomes is called sex chromosomes.

Females have two copies of the X chromosome and males have one X and one Y chromosome. 

An abnormality in an embryo’s chromosomal configuration may cause a specific syndrome to occur or may cause the pregnancy to miscarry. Sometimes embryos are created with too many or too few chromosomes—a condition known as aneuploidy. 

Aneuploidy is a major contributor to miscarriage, in vitro fertilization (IVF) failure, and various health conditions, including Down’s syndrome. 

Accuracy is dependent on the syndrome you are screening for. There is a very small chance the test will not detect an affected pregnancy. There is a small chance (around 0.3%) that the test will incorrectly show a positive result, in this instance we would always recommend diagnostic testing.

NIPT is more accurate than the first trimester NHS combined test or second trimester NHS quadruple test for estimating the risk of genetic disease. However, NIPT is a form of ‘screening’ and is not a diagnostic test. Amniocentesis or Chorionic Villus Sampling are the recommended tests which are diagnostic however, as these come with risks of miscarriage it is recommended to use the no risk NIPT test as the first step. Any concerns during pregnancy should always be discussed with your healthcare provider.

Results that are reported as negative do not eliminate the possibility that the pregnancy has other chromosomal abnormalities, genetic conditions, or birth defects. There is a small possibility that the results might not reflect the chromosomes of the baby, but the chromosomal status of the mother or placenta (a situation known as “placental mosaicism”) or the presence of a tumour (as tumours often have an incorrect number of chromosomes in their cells). 

Results apply only to conditions tested

A negative result means your pregnancy has a decreased chance of having a condition { In most cases, the condition is truly not present (true negative result) { Rarely, the condition may be present (false negative result)

A positive result means an increased chance of having the condition { In most cases, the condition is truly present (true positive result) { In some of these, the condition is not present (false positive result)

Since NIPT is a screening test, results should be taken into context of the overall pregnancy picture and positive results should always be confirmed prior to making pregnancy management decisions.

All NIPT tests can be performed with twins with the exception of NIPT 1.  As with all NIPT test providers, the status of each individual baby cannot be determined, therefore the result will reflect the entire pregnancy. The test can also only report the presence or absence of Y chromosome material (found only in males) but it will not be clear whether both twins are male or just one of them.

Please be aware that a small number of samples can fail the NIPT process when there is not enough fetal DNA in the mother’s blood to extract.”  Trimester 2, 3 and 4 have the advantage of having the lowest failure rates of any NIPT test currently available (0.1%).