Prenatal DNA Paternity Tests
Know the risks
Having a prenatal DNA paternity test does involve risk of harming the baby: birth defects, cramping, infection, leaking fluid and spontaneous abortion or miscarriage are potential effects of prenatal paternity testing. Doing DNA paternity tests postnatal (after the baby is born) involves no risks.
It is strongly recommended that you wait until the baby is born before the baby undergoes DNA paternity testing. In situations where this is not possible, there are three methods to consider for prenatal testing:
- Non-invasive
- Chorionic villus sampling
- Amniocentesis
Non-Invasive
Some labs have begun to offer “non-invasive” prenatal testing. It involves taking a blood sample from the mother and then separating the fetus’s DNA from the mother’s. The methods of testing as well as the claims of equal accuracy to that of amniocentesis or Chorionic villus sampling and testing are now being debated among scientists.
However, there are little to no published results on the methodology used or the accuracy of reporting for non-invasive prenatal testing. Therefore, it is difficult for scientists to significantly debate any scientific claims made at this time. It is strongly recommended, for accurateness and peace of mind, that DNA paternity testing be done after the child is born, using an accredited lab.
Chorionic villus sampling
Chorionic villas sampling (CVS) can be performed 10 -13 weeks after a woman’s last menstrual cycle. A doctor’s consent is necessary for this procedure. It involves taking a tissue sample from the outer lining of the embryo. A thin needle is inserted by a doctor into the vagina through the mother’s cervix. The needle is guided using ultrasound. Chorionic villa are extracted by the needle for DNA testing.
Chorionic villa is tiny finger-like tissue attached to the wall of the uterus. It has the same genetic makeup as the fertilized egg and so the DNA can be tested for a biological match to the alleged father’s DNA.
CVS is not recommended for women who:
- have an infection
- are carrying twins
- have medical concerns during pregnancy, such as vaginal bleeding
- have uterine fibroids
- have a tilted uterus which impedes the catheter
The greatest risk of CVS is miscarriage, occurring in 1 out every 100 procedures. Some sources state that CVS testing accuracy for stating paternal probability is 99%. This is lower than the 99.9% accuracy available from postnatal DNA testing.
Amniocentesis
Amniocentesis can be done during the second trimester of a woman’s pregnancy -- between the 14thand 20thweeks. A doctor’s consent is needed to perform this test. It is strongly recommended you wait until postnatal (after the baby is born) to perform a DNA paternity test to avoid risks of harming the baby or inducing a miscarriage.
Having an amniocentesis involves inserting a needle through the mother’s abdomen into the uterus to extract amniotic fluid. The entire process takes about 45 minutes: an ultrasound is used to determine the safest location to withdraw the fluid. The fluid contains the child’s DNA and can be profiled with the DNA of the alleged father to determine if there is a match.
This process can be painful and is more expensive than postnatal DNA paternity testing because the medical costs are not included in the DNA testing. Accuracy is only 99% compared to 99.9% from postnatal DNA paternity testing. Side effects of the process may include cramping, infection and/or fever. The greatest risk of amniocentesis is miscarriage, which occurs in one out of every 200 to 400 cases.
