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Boy or Girl? Down Syndrome? What to Expect When You’re Testing

News about simple maternal blood tests that can accurately identify the sex of a fetus, genetic disorders, and other traits early in the first trimester are reviving concerns about designer babies and an increased demand for abortion.

A report this week in JAMA finds that maternal blood tests can accurately identify the sex of a fetus as early as the seventh week of pregnancy. Such tests are already available, although their accuracy was uncertain. Last week a San Diego genetic testing company announced that it would market the first maternal blood test to detect Down syndrome in a fetus in the first trimester. The test, given the cute name MaterniT21, is expected to be available in the United States in late this year or early in 2012.

Even before the latest news about these tests, emotions have been running high in anticipation of them soon coming into wide use. Last December, researchers showed that they could do a genome scan of fetal DNA circulating in the mother’s blood, paving the way for prenatal blood tests for a wide range of genetic and chromosomal traits. Marcy Darnovsky wrote in Science Progress that such tests “could radically alter the experience of pregnancy and parenting.” She added, “And we’d better start thinking about it now – before hype, fear, and the polarized politics of abortion distort the discussion.”

Looking ahead to the possible ramifications of a blood test for Down syndrome, a recent article in the New York Times Magazine asked whether children with Down syndrome today may be among the last generation to be born with the disorder.

It’s impossible to know what the effects of these tests will be for parenting and society. But if the exercise of speculation conjures science fiction fears and assumptions ungrounded in facts or ethical framework, I recommend an essayby Ilana Yurkiewicz in Science Progress.

Yurkiewicz aims to cut through the emotional reactions by asking, what’s the problem? What doors are noninvasive early prenatal genetic tests likely to open that are not open already? “If it’s ‘designer babies’ we are worried about, we are already there,” she writes. “Women can now seek egg donors with criteria as specific as ethnicity and minimum height and SAT scores.” Whether these practices really amount to designing your baby is debatable, but in any case the prenatal tests are likely to give parents much more creative control.

On the abortion concerns, she cites statistics that over 80 percent of fetuses diagnosed with Down syndrome in the United States are aborted, as are more than 90 percent of those diagnosed in Europe. “Learning a prenatal diagnosis at nine weeks, in contrast to the 10 to 12 weeks typical for chorionic villus sampling and 15 to 20 weeks for amniocentesis, could alleviate some of the physical and emotional burdens that accompany later abortions, causing these numbers to spike even higher,” she writes. Add to that the benefit that a maternal blood test would probably be safer than the existing tests, which carry the risk of miscarriage.

But she plays down the fear of abortions for what she calls nonmedical traits. “Realistically, much of this theoretical handwriting may prove moot,” she writes. “Are our prejudices so overpowering that we’d pick abortion over a child with the ‘wrong’ height or eye color?”

A large survey of parents conducted in 2009 suggests that the answer is no. The survey asked 1,000 parents at a genetic testing center about the traits for which they would want to do prenatal testing. While 75 percent said that they would want to test for mental retardation and 54 percent would test for heart disease, relatively few said that they would test for nonmedical traits – 10 percent, for example, said they would test for height.

But, in reality, it’s hard to say how prospective parents’ views might change when it is easier and safer than ever to test for all sorts of traits in a fetus. All we know is that the possibilities are emotionally heated. Yurkiewicz ends with a plea for cool heads to prevail. “Detractors do not need ‘what if?’ slippery slope arguments, often accompanied by references to science fiction, to vindicate their objections,” she writes. “They also do not need emotionally charged analogies to heinous past crimes of eugenics to grant them credibility. There are issues in science that have become so entwined with politics . . . that open discourse is vetoed before it can begin. Making moral headway in prenatal testing requires that it doesn’t join those ranks.”

For decades, doctors and expectant parents have wondered if “one day” there will be a “simple blood test” for prenatal testing. That day is almost here. But the implications are anything but simple.

Susan Gilbert is the public affairs editor of The Hastings Center.

Published on: August 11, 2011
Published in: Human Reproduction

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