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For years, mothers wanting to screen for genetic abnormalities in their unborn children have had few options, the most common being an invasive procedure known as amniocentesis, which requires the mother's womb to be tapped with a needle.

That test is very accurate, but also carries with it a small risk of miscarriage. Now, a new, non-invasive genetic screening technique promises to make prenatal testing easier and safer — but it raises a number of important ethical questions.

The new genetic screen is called MaterniT21, and it's a Down syndrome test marketed by a company called Sequenom. Unlike amniocentesis, the MaterniT21 test can be performed with just a small sample of the mother's blood, no womb-jabbing necessary.

While non-invasive screening methods, which can estimate the chance that a woman is carrying a child with Down syndrome, do exist, MaterniT21 is the first to offer the accuracy of a test based on genetic analysis; and as of October 17th, the test is available to physicians upon request in 20 major metropolitan areas across the US.

So why is this a big deal? Well, if reviews like this one (written by Hank Greely, who chairs the steering committee for the Stanford Center for Biomedical Ethics) are to be believed, MaterniT21 is just the first drop in what could soon swell into a "flood" of fetal gene screening, as similar non-invasive genetic analyses are developed for detecting a variety of other conditions.

"There's every reason to think that in the future you'll be able to extract an enormous amount of information from that sequencing data," says Peter Benn, director of the Diagnostic Human Genetics Laboratories at the University of Connecticut Health Center.

Of course, releasing the floodgates on prenatal genetic screening could have any number of consequences. Some ethicists, for example, predict that as it becomes increasingly routine to check for genetic abnormalities, more parents will have to confront the decision of whether or not to bring "unhealthy" children into the world.

"The idea that couples have choices about whether to continue their pregnancies may become strained," explains Mildred Cho, and ethicist at Stanford University, "because parents may be seen as irresponsible for allowing 'defective' pregnancies to go to term."

On the other hand, genetic screens like MaterniT21 could one day be used to not only detect genetic ailments, but could even serve a diagnostic purpose, representing the first step towards actually correcting genetic abnormalities with gene therapies administered in the womb. Whether or not the practice of fetal gene therapy would be considered eugenics raises even more ethical conundrums.

For now, however, Sequenom is seeking to distance itself from the idea of eugenics by focusing on developing tests for conditions that are already included in prenatal screening regimens.

"We do not want to invent new applications," explains Mathias Ehrich, Sequenom's senior director for R&D diagnostics. "Our focus is on making existing clinical applications safer. I don't think that we are in a position to say that we should determine what hair color the baby has."