Science behind the New, Non-Invasive Paternity Test while Pregnant

12 Aug 2017

It is nowadays possible to do a paternity test while pregnant. For many years scientists have known that it is possible to detect the unborn child’s DNA in the maternal blood as an early as in the 10^th week.  Up to recently, this test could only be done with the help of two invasion procedures carried out by the gynaecologist.  The fetal DNA cells were collected by two procedures called CVS Chorionic villus Sampling) and amniocentesis.  Even though these uncomfortable procedures carried certain risks, having them done seemed to suit everybody fine.

The amniocentesis procedure can lead to miscarriage or amniotic fluid leakage.  This CVS – Chorionic Villus Sampling – could lead to birth defects and problems in the limbs of the child.  It is an uncomfortable procedure that involves instrumentation inserted up into the womb.

Fetal DNA finds its way into the mothers blood stream

The growing baby inside the womb of the mother is connected to the placenta.  Soon disconnection the baby receives nutrients and oxygen.  The growing fetus also excretes waste products through this connection.  As the fetus reaches approximately 10^th week, free so DNA is released into the mother’s bloodstream.  With a technology called SNP or “ Single Nucleotide Polymorphisms” scientists are able to detect fragments of DNA and to amplify the fragmented markers.  The presence of the free cell DNA in the mother’s blood stream has been noticed for over 30 years, however until till now, no technology was yet invented for anyone to be able to extract this DNA.   The quantity of the fetal DNA increases in the bloodstream with time.  In fact it is higher in quantity after the 12^th week and reaches a much higher volume after the 25^th week.

The simplicity of getting the non-invasive prenatal paternity test done

There is much less hesitation involved when making a decision to have a non-invasive paternity test in pregnancy done.  There are no more risks that need to be considered.  All is needed is a simple general practitioner or a registered nurse visit to collect the sample.  You can even opt to have an at home nurse come round and collect the sample in the commodity of your own home.  Reputable DNA testing companies would send you a testing kit at home with everything that is needed. Your only job is to fill up the vials with a blood sample (Done by a qualified professional).  It is very important to choose DNA testing company that includes a special delivery of the samples to the testing laboratory.  A courier company on a special laboratory account usually does this.  As the fetal DNA is available in your bloodstream in between the 9^th and 10^th week you are able to proceed with sample collection then.  Waiting until 12^th week does however give you the possibility of submitting a sample with a higher quantity of fetal DNA in it.  This reduces the risk of needing to submit a new a sample to complete the test (Reputable DNA testing companies usually carry out without any additional laboratory fees)

Non-invasive paternity test while pregnant, as accurate as any other

By use of the new technology called SNP or “single nucleotide polymorphisms” scientists are able to detect and extract around 317,000 genetic markers of the free cell DNA fragments in the mother’s blood stream.  It is important to know that no previous pregnancy can affect this test even though intact cells of the previous baby can remain in the blood stream for many years.  In fact that is why the laboratory looks for the free cell DNA fragments and not the intact cells.  Free Cell DNA remains in the bloodstream only during the specific pregnancy.  Scientists are able to compare the genetic markers of fetus to the genetic markers of alleged father.  The result is furthermore strengthened by comparing the outcome of 5000 random unrelated men to the outcome obtained with the alleged father.  This comparison allows the possibility of the probability to be drawn.  If the alleged father’s DNA is as similar to any of the 5000 non-related men tested then he is also not related.  If the alleged father’s DNA is much higher in similarity than any of these 5000 nonrelated men then we can conclude that he is the father of the child.  We can therefore say that the non-invasive paternity test while pregnant is as accurate as any other DNA test out there.