In January 2015, National Public Radio (NPR) released a story featuring the new options non-invasive prenatal testing (NIPT) brings to women in the U.S. The feature, presented by Nell Greenfieldboyce, examines the impact of NIPT on the way previous genetic testing has been conducted and how expectant mothers and healthcare providers are interpreting the results.
Non-invasive tests bring benefit and new considerations
Until prenatal DNA testing hit the market in 2011, the only way women could understand their risk for a genetic disorder was through ultrasound technology and blood tests that looked for specific proteins in maternal blood. Known for their inaccuracies, this approach to testing has been difficult to interpret—sending back results in “ratios” or numbers that expressed potential risk. And the only way to confirm the results was with an invasive procedure like amniocentesis or chorionic villus sampling (CVS)—both of which remain the gold standard for genetic disorder confirmation, but carry a risk of miscarriage.
Thanks to the new approaches in NIPT, women who want genetic testing (but not an invasive procedure right away) can have blood work done that examines fetal DNA circulating in the maternal bloodstream, without putting the pregnancy at risk. If the screening determines a possibility of chromosomal abnormalities, women should work with their healthcare provider and use this information to pursue additional testing to confirm the diagnosis. In her interview with NPR, Dr. Mary Norton, an expert in maternal-fetal medicine at the University of California, San Francisco said, “They’re much more accurate than current screening tests, but they are not diagnostic tests in the sense that amniocentesis is…” The doctor goes on to stress that women should not treat the results of NIPT as 100% accurate and need to follow up with additional diagnostic testing.
The unexpected detection
It’s surprising to many parents-to-be when they discover that non-invasive testing can look for more than genetic disorders like Down syndrome or trisomy 13. The test can also tell you the sex of your baby weeks before an ultrasound. Many parents find this information exciting and look forward to the news, but along with the gender, the test will also reveal information about any abnormalities in the sex chromosomes—like an extra X or Y. According to the article, 1 in every 700 babies has an extra X or Y chromosome and grows normally without ever knowing they have them.
New testing territory for patients and providers
Despite the fact that NIPT has been on the market since 2011, the tests still feel like unfamiliar territory to many healthcare providers. NPR’s medical experts stressed that if you want the test and your doctor doesn’t offer it, continue to look until you find someone who does. Consider checking with local fetal diagnostic centers, maternal-fetal medicine specialists, or genetic counselors who may be well versed in the newest technology.
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