Determining Paternity

What kind of test is done to determine who a child’s father is?

Determining Paternity

Dr. Greene’s Answer:

It is now possible to determine the father even before a baby is born. This is done by comparing DNA molecules — our genetic blueprints. To do this you need a blood sample from both the mother and the potential father (testing without the mother’s blood is possible, but more difficult — and more expensive). You also need a small sample of amniotic fluid (the water that the baby is floating in). Less than 1/4 teaspoon is sufficient for the test. The amniotic fluid may be obtained by a process called amniocentesis. This procedure is performed no earlier than 13 weeks into the pregnancy.

A court order or informed consent of all adults involved is required to proceed with paternity testing.

You will need to wait 3 to 4 long weeks for the results. Waiting for these test results can be a very anxious time. Rush orders take 10 to 15 business days, but cost about $500 extra.

If the test says that the person tested is the father, then he probably is — there is about a 99.8% chance. DNA testing is now legally accepted as able to determine paternity.

Prenatal paternity testing can be arranged through a company called Genelex, located in Seattle, Washington. They are very helpful, and can be reached at 1.800.523.6487. The test costs $700, and is usually not covered by insurance.

If you wait until after the baby is born, DNA testing can be arranged through most local blood banks (many of which use Genelex). The blood sample can be obtained at birth. Otherwise, the baby should be at least 2 months old, since a fair amount of blood is needed for the test. In my area, this option costs about $600, and is usually not covered by insurance.

There is also a less expensive method. For years, the only legally acceptable way to determine paternity was something called Human Leukocyte group A antigen typing, or HLA typing, which looks at the whole complement of proteins found on the surface of white blood cells — and on most cells throughout the body. A person’s HLA type is like her genetic fingerprint. It is how her body determines if an individual cell is a part of her or an invader (a cancer, a virus-infected cell, or foreign tissue). HLA typing technology was first developed in the 1950’s to insure matching in transplant cases. HLA typing is available at blood banks, and although insurance will not cover it for determining paternity, the tests may be obtained for several hundred dollars.

Dr. Alan Greene

Dr. Greene is the founder of (cited by the AMA as “the pioneer physician Web site”), a practicing pediatrician, father of four, & author of Raising Baby Green & Feeding Baby Green. He appears frequently in the media including such venues as the The New York Times, the TODAY Show, Good Morning America, & the Dr. Oz Show.

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  1. Anup Solanki

    Can parents, both blood type o positive, have a child B negative blood group?

    Please tell me.

  2. jenifer

    Is it possible for a baby to be AB positive while one parent is A negative and other is O positive?

  3. Sue

    Can a ‘paternity’ test be done on adult children, when one parent has already deceased? I mean, would I be able to use my Uncle’s blood sample (if he were willing), in place of my Dad’s?

  4. Elaine

    Since Eva was a clone of Adam’s DNA, having his exact same flesh and bone; and blood is manufactured in the bone, how could the three different blood types have evolved? Seems to me it would be a closed repeating loop.


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