Who's your daddy? Non-invasive paternity tests

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Are you the baby’s father?

Q&A with Dr. Manny: I’m not 100% sure who my baby's father is. Are there any non-invasive options to find out before he/she is born?

DNA paternity testing is the methodology whereby DNA is obtained and evaluated to determine whether two individuals are biologically parent and child. A paternity test determines if a man is the biological father of an individual; likewise maternity testing establishes whether a woman is the biological mother of an individual.

DNA testing is currently the most commonly utilized technology to ascertain parentage.

Paternity testing confers a number of benefits--primary of which is to establish a medical history,  to establish inheritance, legal or social allotments.

There are two types of paternity testing: postnatal paternity testing, which occurs after the baby’s birth, or prenatal paternity testing, which is performed while the mother is pregnant. Postnatal paternity testing can be performed by obtaining a blood sample or a buccal swab of the proposed father, in conjunction with either an umbilical cord blood sample at birth, or a blood specimen/buccal swab from the infant after birth, and prior to discharge from the hospital.

With prenatal testing, there are two types available: Invasive and non-invasive.  Invasive testing can be done in two ways-- either via CVS (chorionic villus sampling), which uses a needle , generally through the cervix within the first trimester of pregnancy to obtain chorionic villi, or via amniocentesis, which involves using a needle inserted through the pregnant abdomen in the second/third trimester to obtain amniotic fluid, which contains fetal cells for analysis. This is done in conjunction with obtaining either a blood or buccal specimen from the proposed father. There is a small risk of miscarriage associated with an invasive evaluation.

Non-invasive prenatal testing (NIPT) involves obtaining blood from the mother in conjunction with obtaining either a blood or buccal specimen from the father. Fetal DNA can be observed in the mothers' blood as early as 7 weeks gestation. The amount of fetal DNA retrieved by this method can vary depending on the mother’s weight. There is no risk of miscarriage with this form of testing.

A paternity test is not currently 100 percent accurate.  With a DNA percentage test, the result, which is deemed the "probability of parentage", is 0 percent when the alleged father of the baby is not biologically related. The result is typically 99.99 percent when the alleged father of the baby is biologically related to the child.  Very rare individuals may have two separate sets of genes, also known as chimeras, as opposed to a single distinct set, which can result in a false positive test.

There are a small number of companies within the U.S. that offer prenatal paternity testing--Raven, DDC, Accu-metrics, and Natera are among them. The cost ranges from $1400-$2000. Most insurance companies do not pay for paternity testing; a caveat is if there is concern for a particular genetic disorder--in either case, its best to confer with your insurance company directly.

Dr. Kecia Gaither is a double board-certified physician in OB/GYN and Maternal Fetal Medicine and holds a Masters' degree in Public Health.