What are the Different Methods of Fetal Paternity Testing?

To determine who the father of her child is before the baby is born, an expectant mother may choose to perform fetal paternity testing. Establishing paternity before giving birth can be done using three methods. Two invasive methods, which can be done at the same time as other tests, involve extracting fluids from either the placenta or the amniotic sac. If, for some reason, the mother does not wish to have or can not have these procedures done, she can opt to have more non-invasive fetal paternity testing done.

Fetal paternity testing can be done using samples from a chorionic villus sampling, or CVS. This test is typically done as early as 10 weeks into the pregnancy until 14 weeks into the pregnancy. Using this method, chorionic villi cells, which contain fetal DNA, are extracted from the placenta. The DNA is then compared to the father's to establish paternity. The results of this test are said to be almost 100 percent accurate.

There are two methods by which these cells can be extracted. In a transcervical procedure, a very thin catheter is guided through the mother's cervix with the aid of an ultrasound. The cells are then suctioned up and collected. During a transabdominal procedure, an ultrasound is also used, but instead of going in through the cervix, cells are collected by going in through the mother's abdomen. Using a thin needle, the obstetrician guides the needle to the placenta and extracts a small amount of these cells.

Using a procedure known as amniocentesis, obstetricians can also perform fetal paternity testing. This procedure is typically done between 14 and 24 weeks into the pregnancy, and involves collecting a sample of amniotic fluid. Like CVS fetal paternity testing, the DNA collected is compared to the father's and this test is considered to be very accurate.

During this procedure, the obstetrician uses an ultrasound to search for a safe place to stick a needle into the mother's abdomen. After a safe entry point is located, a long, thin needle is inserted into the mother's abdomen, after a local anesthetic is administered to numb the area. When the amniotic sac is pierced, a sample of the amniotic fluid is taken. This fluid contains shed cells of the fetus. These cells are isolated from the fluid and used in prenatal paternity testing.

Recent research has determined that some of an unborn baby's DNA transfers into the mothers blood stream through the placenta. A relatively new procedure has been developed, called fetal cell/DNA fetal paternity testing, which can usually be done anytime after 14 weeks. During this prenatal paternity test, a sample of the mother's blood is taken, and the DNA of her child is isolated from it. It is then compared with the DNA of the father. Although this procedure is a bit less expensive and considered to be non-invasive, it is not considered as accurate, and many times the test results are not allowed as court evidence.