When a prenatal paternity test is "unreliable"

A journalist called a prenatal paternity test "unreliable," "inaccurate" and "prone to error." He was sued for libel. But in his ruling, the judge agreed. Why is the test still for sale?

Ten years ago, New Scientist magazine published a story claiming that a prenatal paternity test was yielding unreliable results. A man had been incorrectly identified as the father, the article alleged, and another had been incorrectly excluded. The company in question, based just outside Toronto, sued for libel.

Almost eight years passed before the case was heard in a Toronto courtroom in the spring of 2018. I was able to attend about half of it. In December 2018, the judge found in favour of the journalist. In April this year, appeals exhausted, the case ended.

Below, I summarize the allegations made by the journalist, Peter Aldhous, and the judge's ruling. But before the summary, I want to make two important points. 

First, it was a journalist — not Health Canada, our supposed regulator — who brought this matter to light. Without that painstaking work, we would not know about this.

Second, this prenatal paternity test is still available for sale.


(Full disclosure: Peter Aldhous, the journalist who investigated and wrote the piece in question, was an editor of mine at New Scientist in the late nineties.)


In December, 2010, an article in the British science weekly, New Scientist, alleged that a Canadian prenatal paternity test was "unreliable." 

The article, by Peter Aldhous, described instances in which the results were incorrect. In one case, a woman wanted to know which of two men was the father of the child she was carrying — her boyfriend or another man. The test results suggested it was the other man, at which point she considered termination. But a second, more conventional, test found that the other man could not be the father. 

Another case involved a man who was incorrectly deemed to be the father. That man gave up his plan to go to law school, moved in with the mother, and helped raise the child. Two subsequent tests revealed, however, that the child was not genetically his.

People seeking prenatal paternity testing are often doing so in order to make an important decision — to terminate a pregnancy, for instance, or to involve another person in the intimate act of co-parenting. Accuracy is paramount.

At the time of both these cases, the standard was to use amniocentesis, which involves inserting a needle into the uterus and collecting fetal cells from the amniotic fluid, which can then be analyzed. Amniocentesis carries a small risk of miscarriage. What was especially appealing about this new test was that it required only a blood sample from the mother and a cheek swab from the purported father. It cost around $950.

Despite the fact that different companies appeared to be offering the test, when Aldhous began investigating, he found they were all being performed by a Toronto-area company called Health Genetic Center (HGC). As part of the New Scientist investigation, which lasted some 18 months, Aldhous spoke with numerous scientific experts. As well, he and two colleagues — another man, and a woman who had never been pregnant — submitted samples to the company for testing. The results erroneously indicated that there was a fetus and that Aldhous was the father.

"Our findings highlight the potential dangers of allowing companies to operate without regulation and quality control," he wrote. "Paternity testing labs are free to operate without accreditation unless they offer results for use in court."

Not long after New Scientist published the story in December 2010, the company sued for libel, naming Aldhous, the magazine, and the magazine's then-owner. A trial took place in Toronto in March and April of 2018. In his ruling, the judge wrote, "There were fourteen cases in which follow-up tests were conducted by accredited laboratories where these subsequent tests demonstrated that the results reported by the plaintiffs were wrong... The fourteen cases demonstrate that the test is unreliable, inaccurate and prone to error. This serves to confirm that the defence of justification has been made out. On this basis alone I can, and I do, dismiss the action." Only in April this year, however, following appeals, did the case finally come to a close. 

In a follow-up piece published this past weekend in BuzzFeed, Aldhous tells the story of yet another couple given incorrect results by the test — in 2017. The test, he writes, is still for sale.

"The DNA testing industry is largely unregulated," Aldhous writes. "In the US, Canada, and other countries, companies are allowed to sell DNA tests without going through the approval process required for prescription drugs or medical devices. They don't need to provide any scientific data confirming that a new test, whether used for medical diagnosis or to prove paternity, actually works as advertised... My protracted legal battle shows that this needs to change."


Original 2010 story:

Peter Aldhous. "The danger of unreliable paternity tests." New Scientist. 01 Dec 2010. 

Follow up 2020 story:

Peter Aldhous. "Pregnant Women Have Received False Results From This DNA Paternity Test." BuzzFeed. 04 Jul 2020.

Twitter thread about this story


Contact me at alison.motluk@gmail.com

Follow me @AlisonMotluk and @HeyReprotech 

Check out the HeyReprotech archive