You don't have to wait for a child to arrive to establish who the father is--or isn't. The same DNA paternity testing used for children after they are born is available for fetuses in utero. The challenge is in getting a DNA sample from the fetus. Two common procedures used to check fetuses for birth defects can also be employed for paternity testing.
Time Frame
Prenatal paternity testing can be performed as early as 10 weeks into pregnancy if you use the test known as CVS. Once a suitable DNA sample has been drawn, you should get test results within about five days, according to the American Pregnancy Association.
Types
To obtain genetic material from the fetus for paternity testing, a pregnant woman undergoes one of two procedures: chorionic villus sampling or amniocentesis. These are the same procedures that doctors use to test fetuses for chromosomal abnormalities and other genetic disorders.
Chorionic villus sampling, or CVS, becomes available about 10 weeks into pregnancy and can be performed up to about 12 or 13 weeks. In this procedure, a doctor inserts a needle either through the abdomen or through the cervix and takes a sample of a type of placenta tissue called chorionic villi. Since these tissues, like the fetus, develop from the fertilized egg, they have the same DNA as the fetus, so they can be used for paternity testing.
Amniocentesis is available starting about the 14th or 15th week of pregnancy. A doctor inserts a needle through the abdomen into the uterus and takes a sample of the amniotic fluid that surrounds the fetus. This fluid contains fetal cells whose DNA can be used for paternity tests.
Some labs offer what they call "non-invasive prenatal paternity testing," which they claim can obtain fetal DNA just by drawing a blood sample from the mother. AABB, the organization that accredits DNA-testing labs, does not consider these tests reliable.
Accuracy
Positive DNA paternity tests--those that say a certain man is the father of the child in question--are more than 99 percent accurate, according to the Cleveland Clinic. Further, DNA testing can say with 100 percent certainty that a given man is not the father of a child.
Cost
The American Pregnancy Association says the cost of DNA paternity testing at an AABB-accredited laboratory depends on the area of the country where you live and the type of test you want done. Testing that meets standards for admissibility in court will be more expensive than "curiosity" testing designed to give you a quick yes-or-no answer. As of mid-2010, the association offered a general range of $400 to $2,000 for the DNA testing, on top of the cost of the medical procedure to obtain a fetal DNA sample.
Risks
Though CVS and amniocentesis are generally considered safe, they do carry an elevated risk of miscarriage. The Mayo Clinic cites research that identifies the miscarriage risk at between one in 300 and one in 500. The risk is higher for amnio conducted before 15 weeks. Mayo says the miscarriage risk of CVS is about one in 100; the risk is "slightly higher" if the needle goes in through the cervix rather than the abdominal wall. Both CVS and amnio carry slight infection risks, and cramping and vaginal bleeding can result.
