A paternity test can be performed in pregnancy if there is any doubt regarding the identity of the father. The test involves looking at the DNA of the fetus and comparing it to the DNA of the mother and all potential fathers. DNA is the genetic code inherited from both parents, which gives the body instructions about features (such as eye colour). Depending on whether the DNA of the fetus matches that of the potential father, the test can determine, with a very high degree of accuracy, the identity of the father.
How is the test performed?
In order to get a sample of DNA from the fetus, an invasive procedure such as a Chorionic Villus Sampling, or an Amniocentesis needs to be performed. These procedures are commonly used to obtain a sample of fetal DNA to test to see if the fetus has Down’s Syndrome.
Although they are routine procedures, they do involve inserting a needle into the womb and both run a risk of miscarriage (1:200). Therefore, when considering having a paternity test in pregnancy, it is important that the best interests of the baby are considered at all times. Everyone involved needs to understand what the test means, the risks of the procedure and that the results can have a serious emotional impact, particularly if they are not the results that are expected or wanted.
What does the Paternity Test appointment involve?
In view of the risks inherent in the test, an appointment for a paternity test in pregnancy would involve a detailed consultation with a Fetal Medicine Specialist, to establish whether a test is indeed needed and its implications. This consultation should be attended by the mother as well as at least one if not all the potential fathers. If following the consultation a paternity test is still required, the amniocentesis or CVS would be performed by the Fetal Medicine Specialist and blood samples are taken from the mother and the potential father(s). All the parties being tested will need to give their written consent.
The samples will then be sent to the laboratory and the results should be available in 5-10 days. If the mother wishes a test for Down’s Syndrome it can be performed at the same time by the laboratory.
How accurate is parentage testing?
If the generic profile between the potential father and child does not match, then this potential father is definitively not the father of the pregnancy with a certainty of 100%. If the genetic profile between the potential father and the child matches, then he is likely to be the father, with a certainty of >99.99%.