Prenatal paternity testing enables one to determine paternity before the birth of a child and is a very conclusive means of determining paternity. If you do not wish to wait for the child to be born to carry out the test, then you may want to consider doing your test while pregnant. Depending on the stage of pregnancy, different DNA sampling procedures are required. The cost of a prenatal DNA paternity test normally involves the cost for the laboratory analysis and the cost of the sample extraction by an Ob-Gy.
How are the DNA samples collected in Prenatal Paternity Testing ?
Prenatal DNA testing involves an invasive method of sample collection and this can involve one of two procedures. These two methods can be used for both paternity testing and prenatal genetic screening.
CVS, or Chorionic Villus Sampling: this involves entering the womb and can be done in two ways: either transcervically (through the vagina) or transabdominally (through the abdominal wall). The obstetrician or gynecologist enters the womb guided by an ultrasound. Once the placental wall is reached, a DNA sample can be taken (the placenta is the thin wall which envelopes the fetus) .
When can CVS be carried out?
Chorionic villus sampling takes place between 10-12 weeks after the last menstrual cycle. This prenatal testing carries certain risks, mainly the risk of miscarrying which lies somewhere between 0.5-1%. The point of venepuncture can also be an area that may develop infection and further to this, in rare cases there may be leakage of the amniotic fluid.
Amniocentesis: this test involves withdrawing around 20 ml of amniotic fluid from the sac surrounding the fetus. The procedure is sometimes done under local anesthetic. This sac contains loose fetal cells that float around in the fluid. DNA can be isolated and extracted from these cells and a paternity DNA test carried out. Sampling takes places transabdominally which means that the obstetrician or gynecologist will extract DNA by inserting a needle through the abdomen guided by an ultrasound. Once the DNA is extracted, the paternity test can be carried out. However, DNA analysts must first separate the fetal cells from the rest of the sample or fluid in which the cells are suspended.
When can Amniocentesis be carried out ?
This form of fetal DNA sampling takes place between the 14th-24th weeks of pregnancy. There are certain risks which are peculiar to amniocentesis although these are rare. Risks include damage to baby’s limbs, leaking of the amniotic sac or in some cases miscarriage. There are specific medical tests which should be rigorously followed up so as to ensure the pregnancy is going well after CVS or amniocentesis has been carried out.
A few words on boy or girl Gender Prediction Testing
Whilst a boy or girl gender prediction test is carried out in the prenatal stage (that is, before the birth of the child) it is not strictly considered a prenatal test. The sampling method to determine baby gender is far more simple and the method of DNA analysis is also less complex then happens in prenatal testing for paternity. In fact, all one needs to know the gender of their baby is a sample of urine from the mother. Also, a DNA test to find out if you will have a boy or a girl can be carried out earlier in the pregnancy then a DNA test to determine paternity.
Non-invasive Paternity Testing
It is possible to sample fetal DNA from the mother’s blood. This new technique has been recently developed although scientists have known for a long time that in the mother’s blood there are traces of the DNA belonging to the child she is carrying. Scientists can extract a blood sample and separate the mother’s DNA from that of the child. Some companies claim they can determine paternity using non invasive DNA testing as early as 12 weeks. However, this test has still not become mainstream and results have not been consistent enough to make it a reliable means of determining paternity of an unborn child. This is partly due to the fact that there may not always be enough fetal cells in the blood to conclude the test.
How accurate is a Prenatal DNA Paternity Testing ?
A prenatal paternity test is not any less accurate than a paternity test done after the birth of the child. Just like a standard paternity test, inclusion of the mother’s DNA sample will help provide more accurate results. Having the mother’s DNA allows analysts to clearly eliminate her share in the genetic inheritance of the child, thereby working only with the DNA profiles of the alleged father and child. If the tested alleged father is the biological father of the child, the prenatal DNA test will show a probability of paternity higher than 99.99%. Conversely, if the alleged father is not the biological father of the child, the probability of paternity will be 0%.
Prenatal DNA testing can thus be used to determine paternity or to trace genetic diseases in the unborn child; prenatal tests can be either invasive or non invasive. If you are considering this type of paternity test it is important to understand the invasive and non invasive aspect of it.