The Short of It
Since 2011, hundreds of thousands of pregnant women have used new noninvasive prenatal tests, which screen placental DNA found in the mother's blood, with no reason to doubt their effectiveness. But the fact is, positive results can be wrong in 50 percent of tests. This means that it's likely that women have aborted their babies based on the results of these tests, which could have been false positives.
Like many expectant couples these days, Zachary Diamond and Angie Nunes of Portland, Ore., were encouraged to use new noninvasive prenatal blood screening. The doctor said the test was "99 percent" accurate in predicting chromosomal abnormalities. The results said the fetus had Trisomy 18, a genetic condition that is fatal. They were devastated and prepared for the worst, but another test revealed that the baby was "probably" fine. Today, they're holding a completely healthy baby in their arms.
Many women have had false negative results too. Belinda Boydston, 43 of Chandler, Ariz., was urged by her doctor to take a noninvasive prenatal test after a 20-week ultrasound showed her fetus had heart defects. The screening showed no chromosomal abnormalities, but when her son Hunter was born in January 2014, he had Trisomy 18 and died within four days.
The companies who produce these noninvasive tests are aggressively marketing the screening tests to women of all ages without making patients or doctors aware of their limitations. Moms-to-be, especially those of advanced maternal age, are very eager to learn if their fetuses are healthy, and since amniocentesis can pose a risk of miscarriage, noninvasive screening sounds like a miracle. They take the tests without realizing that to be completely sure of a diagnosis, they still need to undergo amniocentesis or chronic villus sampling.
These prenatal tests don't require FDA approval because of a regulatory loophole. In July, the FDA announced it would begin to regulate hundreds of medical tests, but it could take years to take effect.
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