Legal paternity tests are crucial in order to identify a child's father and get financial benefits, such as child support or inheritance money. Such tests need to be performed by professionals, typically using DNA samples, rather than just at home using test kits. For those who want results before the baby is born, prenatal testing can be done, typically through either amniocentesis or chorionic villus sampling. Waiting until the child is born to perform legal paternity tests is also possible, and involves collecting DNA from blood, hair, tissue, and more.
One of the most commonly used legal paternity tests is called amniocentesis. This can be performed only in the second trimester, specifically from week 14 to 20 for the most accurate results. As the name indicates, the amniotic fluid is tested after being collected using a long, thin needle. Since the needle is injected through the abdomen, there is a risk of hurting the baby during testing, but most doctors use an ultrasound to help guide the needle so that this risk stays low. It should be noted that most insurance companies will not pay for this test unless it is medically necessary, such as to test for genetic disorders.
Another type of paternity test is chorionic villus sampling, also called CVS, which can be performed during the first trimester between weeks 10 and 13. This test involves putting a thin needle through the cervix and into the uterus. The point of this test is to collect chorionic villi, which are tiny pieces of tissue that are part of the uterine wall. Since they come from the same egg as the fetus does, they should have the same DNA, so the villi can be collected and tested to determine the father. Similar to the amniocentesis, the CVS can be risky, but the guidance of an ultrasound can help keep risks very low.
There are a few legal paternity tests that can be done after the baby is born, and they tend to be less expensive than prenatal testing, and are also less complicated and carry fewer risks. They all involve collecting DNA from the father to compare it to the genetic makeup of the baby, and there are various ways to go about this. Typically, blood is collected and tested, but semen, tissue, and hair can also be used. Additionally, it is possible to swab the cheek and collect cells that way, or take cells from the umbilical cord of the baby in order to compare them to the father's DNA through legal paternity tests.