Prenatal paternity testing can be either invasive or non invasive. Given the fact the non invasive prenatal paternity testing is a recent field of research and the test has only recently been made available by a handful of DNA testing companies. It is likely that in future the availability of the non invasive prenatal DNA tests will be more widespread, but currently, it is only USA-based laboratories that are offering the test.
What exactly does non invasive paternity testing mean?
It is crucial to understand that prenatal paternity testing methods have until recently only been of the invasive type. By invasive prenatal testing, we refer to such methods of fetal DNA sampling as amniocentesis and chorionic villus sampling. These tests offer an excellent fetal DNA sample but the method of extraction somewhat complicates things. Both an amniocentesis and chorionic villus sampling, referred to as CVS in short, require piercing of body tissue or the insertion of catheters which are in both cases placed within very close proximity of the unborn baby. This, as mentioned, may cause complications including fetal trauma, damage to the fetuses’s limbs and miscarriage.
Non invasive prenatal paternity testing is a zero risk test. The fetal DNA sample is collected from the maternal blood stream and there is no contact whatsoever with the womb, the cervix, the fetus to mention but a few that are involved in invasive prenatal paternity tests.
Blood samples for non invasive testing can be collected via a medical blood draw from the median cubital vein (the vein that runs on alongside the back side of your entire arm). The samples of maternal blood are then sent to the laboratory.
The laboratory will analyze some 300,000 single nucleotide polymorphisms from the cell-free DNA found in the maternal blood. The test is extremely accurate and offers probability inclusions of paternity (meaning the alleged father is the biological father of the child) that are 99.9% or higher.
Levels of Fetal DNA: taking the non invasive prenatal paternity test
The amount of cell-free fetal DNA increases exponentially as pregnancy progresses. This is an important point: fetal DNA is present in the maternal blood stream starting from the earliest stages but the quantities are too small to be detected. It is therefore important to carry out the test starting from the 10th week of pregnancy.
Remember that weeks of pregnancy are calculated starting from the first day of your last menstrual period not from conception which takes place two weeks after your LMP. Taking the test too early might give you an inconclusive result.
Sampling for Prenatal Paternity Testing
Sampling for this type of test must be done a qualified phlebotomist or nurse or any other person in the field. Blood samples must be sent off with a short time of the blood being taken this will help maximize the accuracy of the test. You will need to use one of the kits supplied by the DNA testing company as you will require a special hazardous sample label as well as blood collection tubes.
Typically, it is recommended that both alleged fathers are tested but in most situations it is only one father who is available for the test. It is important to note that even the alleged father will need to submit blood samples which means that there is no covert or discreet way of going about a non invasive prenatal paternity test.