The CBC recently published a story promoting a urine-based test to determine the sex of a fetus during pregnancy. Although the article claims the kit has an 80-92% accuracy based on three studies, no citation was provided and there was clearly no assessment of the quality of these studies (if they exist). While this should have been the focus of controversy surrounding the article, a controversy was instead manufactured surrounding the name of the product: GenderSense.
Rather than relying on a qualified OB-GYN to discuss the nature of this sort of testing, the author interviewed a sociology professor from Wilfred Laurier. While the professor pointed out the issues in conflating gender as a social construct and sex as a biological trait (and I mean – come on – it’s not 2012, people), there was no discussion contextualizing the product medically. When is sex normally determined via ultrasound? How does this time frame and accuracy compare with the proposed product? How will this knowledge empower the consumer to make decisions going forward? Perhaps the company could have avoided this distraction by naming the product SexSense. Then again, that name sounds more like something you’d see in your spam folder rather than a pharmacy.
Like most journalists, I don’t know a damn thing about reproductive health. Unlike many journalists, however, I am concerned with the accuracy of scientific and medical claims. So, time to learn a thing or two.
First, we should establish why sex determination is important. The most obvious answers are for social reasons: preparing psychologically, shopping, religious reasons, and even just plain curiosity. While we can debate the validity of these reasons and their potential consequences, there are also good medical indications. There are numerous sex-linked disorders that a fetus could be predisposed to, either necessitating prompt medical intervention, or potentially forming part of an informed decision in the choice to terminate a pregnancy. The ethical considerations are vast and there is no way I’m touching those. So, how do we determine sex?
As it turns out, prenatal biological sex is not trivial to determine. Although there are many exceptions – especially in cases of genetic anomalies and divergence between genotype and phenotype – sex is generally best determined by identification of the sex chromosomes (XX vs. XY). The gold standard test is a sampling of the chorionic villi, however, this procedure does not come without risk, including a very small increased risk of miscarriage. Amniocentesis is an alternative test that comes with similar low, but quantifiable risks. As a result, secondary measures are preferred, such as the examination of physical traits or testing of cell-free fetal DNA, which are both rather accurate and safe.
How accurate are these measures? The answer is: it depends on how far along the pregnancy is. Obviously it would be great to know at the time of conception, but the unfortunate reality is that we don’t live in a world where techniques like Chinese Astrology are anything more than chain email content or Reader’s Digest filler. Instead, we have to wait for the expression of traits that our science-based tools actually measure.
In the case of ultrasound – while generally inaccurate in the first trimester – the accuracy of sex determination greatly improves between weeks 11 and 13 (nearing 100% if anomalous cases are excluded). While the procedure is evolving with newer, higher resolution imaging technologies, it has historically relied on a simple premise: is there a penis? Obviously, the modality is very dependent on physical characteristics, which do tend to vary.
Cell-free fetal DNA testing is a bit more interesting. This is fetal DNA circulating in maternal blood that is sampled with a blood test. The obvious limitation is the requirement for enough fetal DNA to be in circulation, which most certainly is not the case at the moment of conception. A recent review indicated that the test was unreliable if performed before 7 weeks of gestation. Interestingly, the authors also concluded that urine testing for cell-free fetal DNA was unreliable. Is any urine testing reliable?
Scouring the literature, there were no conclusive studies that supported any form of urine testing for sex determination. Despite this, many products south of the border have made bold claims regarding the efficacy of their urine tests. Experts appear to conclude that these test are entirely bogus.
One particular product bears a remarkable resemblance to GenderSense; IntelliGender claims to be the “first in-home Gender Prediction Test.” Let’s compare the products:
|GenderSense Claim||IntelliGender Claim|
|Type of Test||Urine-based prenatal sex determination||Urine-based prenatal sex determination|
|Alleged Evidence||Three Studies||Internal lab trials plus two independent trials|
|Colour Indicator||Orange or yellow for a girl, green for a boy||Orange or yellow for a girl, green for a boy|
|Earliest Claim of Efficacy||10 weeks||10 weeks|
|Wait Period After Mixing||About 5 minutes||5 minutes|
|Retail Price||45 USD||Around 40 USD|
While these are some pretty striking similarities, it’s worth noting that there is one big difference between the two products; new to the market, GenderSense has yet to be on the receiving end of legal action for selling a misleading and dangerous product. That’s right; IntelliGender was found to rely on lye, aka Drano, aka sodium hydroxide – a caustic chemical that was likely the cause of multiple explosions. Ultimately, IntelliGender was ordered to pay penalties in the amount of $250,000 for marketing a product attorneys for the city of San Diego called “nothing more than Drano in a pretty box.” While there appears to be no published evidence of efficacy, experts concluded that the test results were “about the same accuracy as a coin toss or random guess.”
Does GenderSense have anything better to offer? The purported studies might have the answer, but I won’t hold my breath for their release. After all – as with IntelliGender – GenderSense’s founder Remy Warren does not possess any formal scientific or medical training. Business as usual.
Because the product does not claim to treat a medical condition or make a diagnosis, Health Canada has announced that it will not pursue regulating the device. They make a fair point, but who is to regulate the science of this pseudo-medical product? What happens if parents rely on this information to make medical decisions? Regardless of the implications of knowing the sex of a fetus, the implications of making the wrong assumption could be dire.
It would have been nice if these issues were raised by the CBC. Then again, if it weren’t for bad science reporting, I wouldn’t be learning so much about fetuses.
Thanks to Dr. Terry Polevoy for his investigative work and commitment to Canadian health issues. Remy Warren was contacted prior to the release of this article, but I have not yet received a response.