New paternity test pinpoints father 8 weeks into pregnancy

The non-invasive procedure improves upon existing pre-birth paternity tests that carry a small risk of inducing a miscarriage.

Nature didn't make it easy to figure out who the father of a child is. But science now can.

In instances when a prospective mother is uncertain about the paternity of her child, a new, reliable test can determine it even in the first few months of fetal development.

Furthermore, the test can pinpoint paternity using a non-invasive procedure; existing reliable pre-natal paternity tests such as amniocentesis are invasive and carry a small risk of miscarriage.

How the tests works

The tests require blood samples from the mother and from one of the prospective fathers (if there are two), and doctors may not even have to get involved. The test then measures DNA fragments from the fetus that will be present in the mother's blood.

(This method is also what enables a fetus's entire genome to be decoded from a mother's blood sample and a father's saliva .)

Although noninvasive prenatal paternity tests have been offered on the Internet for about a decade, users of those have complained about inaccurate or fraudulent results.

An experiment with a small sample size showed the new test to be reliable: The New England Journal of Medicine published results showing that the test accurately determined paternity in 30 cases.

That study was of a paternity test by Ravgen, a small Maryland company that has been offering its test for $950 to $1,650, depending on the circumstances, according to The New York Times.

Another test offered by a Silicon Valley company called Natera costs $1,775, and is marketed by the DNA Diagnostics Center, which specializes in conventional paternity tests. The results of the Natera test's accuracy have not been published in any peer-reviewed journals.

Additionally, neither test has been certified by the American Association of Blood Banks for the accuracy necessary for child custody cases; the AABB is currently considering whether to certify prenatal tests.

The impact of prenatal paternity tests

The pregnancy "discrepancy rate" is -- the percentage of pregnancies in which the presumed father is not actually the biological father -- It is not known exactly. Studies have come up with figures ranging from 0.8% to 30%, with the median being 3.7%.

Whatever the exact number, there are a few consequences these reliable, noninvasive prenatal tests could have: First, they could vastly expand testing, Sara Katsanis of Duke University’s Institute for Genome Sciences and Policy told The Times.

Second, early testing could increase paternal support for pregnant women, since as one woman who was uncertain of her child's paternity told The Times, “Neither [of the possible fathers] really wanted to be involved and then find out the baby wasn’t theirs later.” After she got the test, the father attended the delivery and supported the child.

Another possibility is that they increase the number of abortions, as mothers find out that their unborn fetuses are not the children of their desired fathers. However, Ravgen's chief executive, Dr. Ravinder Dallan, also surmises they will prevent abortions by mothers who have been raped, if they find out the father is not the rapist.

Likely, the impact will be a combination of all the above.

What do you think? Do you think that the tests will benefit mothers and babies, and that the good of those tests will outweigh the bad of any increase in abortions? Or do you think that the tests will only increase abortions, not support for the mothers and children?

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via: The New York Times, New England Journal of Medicine

photo: Drawing by Leonardo Da Vinci (Wikimedia)

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