When a distraught pregnant woman phones a Massachusetts hotline for Down syndrome, agonizing over what to do with an unexpected prenatal diagnosis, she will be routed to Perkins McLaughlin, who went through the same awful calculations in 2007. When Perkins McLaughlin learned halfway through her pregnancy that her daughter would have Down syndrome, she nearly decided to end the pregnancy for fear of what it would do to her marriage and her two older children. [...]
But now, increasingly, parents do. Recent advances in prenatal screening are upending the way pregnant women learn about the genetic makeup of their unborn babies. In October, a San Diego biotech company began offering an exceptionally accurate maternal blood test for Down syndrome that can be administered as early as 10 weeks, long before a woman looks visibly pregnant. A study published last month in the journal Genetics in Medicine found that the DNA-based test, called MaterniT21, identifies 98.6% of Down syndrome pregnancies, with a false-positive rate of 0.2%, an achievement that study author and Brown University professor Jacob Canick hailed as a "major step for prenatal diagnosis."