Prenatal Paternity Testing | Invasive and Non Invasive tests
Prenatal paternity testing can be either invasive or non invasive. Most women are more familiar with invasive prenatal testing procedures such as amniocentesis and chorionic villus sampling. This is because these tests, besides being used for paternity testing, are also diagnostic tests which are often used to confirm whether an unborn baby will suffer from any hereditary illnesses.
Amniocentesis and Chorionic Villus sampling: A summary of Invasive Tests
Amniocentesis is usually done under local anesthetic. An obstetrician/ gynecologist will insert a needle through the abdomen to withdraw a sample of amniotic fluid. Amniotic fluid is the amber-coloured liquid that surrounds the baby and which contains large quantities of fetal DNA. An ultrasound is used to assist the surgeon insert the needle in the correct place.
Chorionic villus sampling involves taking a sample of the chorionic villi- these are microscopic finger- like structures which line the wall of the placenta. The surgeon enters the womb through the vagina rather than through the abdomen as happens during amniocentesis. Chorionic villus sampling also takes place later during gestation.
Once the sample is collected, the baby and the mother’s DNA profile is mapped. The DNA profile of the child is compared to the DNA profile of the alleged father. A match between the 2 DNA profiles confirms the alleged father as the biological father of the child.
Both Chorionic Villus sampling and Amniocentesis are invasive tests; they carry certain risks, which though small are still real. The risks include damage to the limbs of your child, leakage of amniotic fluid or in some rare cases, miscarriage. Apart from that there is a cost associated with collecting the sample.
Non Invasive Prenatal Paternity Testing
A prenatal paternity testing method is nowadays available which requires a simple blood withdrawal. It is known that a pregnant mother carries quantities of DNA belonging to her baby in her blood stream. The placental wall allows exchange of nutrients, elimination of waste and gas exchange but dead placental and fetal cells also find their way through the placenta and into the maternal peripheral blood stream. The amount of fetal DNA in the maternal blood stream increases as pregnancy progresses. An average blood withdrawal of maternal blood will contain anywhere between 3-12% in fetal DNA fragments.
Once the fetal DNA has been isolated, laboratory DNA analysts can map some of the baby’s genetic markers. This non invasive prenatal paternity test has invariably shown a high rate of success in establishing the paternity of a child.
Can I find out the gender of the baby?
No, a prenatal paternity test is solely aimed at determining whether the tested alleged father is the biological father of the unborn baby. You will either need to wait for an ultrasound to know the gender of your baby or carry out one of the 2 main types of DNA-based gender tests.