About a decade ago, companies began offering pregnant women tests that promised to detect rare genetic disorders in their fetuses.The tests initially looked for Down syndrome and worked well, but later tests for rarer conditions did not. An investigation has found that the grave predictions made by those newer tests are usually incorrect.We look at why the tests are so wrong and what can be done about it.Guest: Sarah Kliff, an investigative reporter for The New York Times. Sign up here to get The Daily in your inbox each morning. And for an exclusive look at how the biggest stories on our show come together, subscribe to our newsletter. Background reading: In just over a decade, prenatal tests have gone from laboratory experiments to an industry that serves more than a third of the pregnant women in America. The grave predictions of rare genetic disorders made by newer tests, however, are usually wrong.For more information on today’s episode, visit nytimes.com/thedaily. Transcripts of each episode will be made available by the next workday.