The screening would allow some women with high-risk pregnancies to avoid amniocentesis as well, said Diana Bianchi, executive director of Tufts Medical Center's Mother-Infant Research Institute.
Physicians currently recommend that all pregnant women undergo screening for Down syndrome, and it is recommended that those with positive results undergo amniocentesis, in which a long needle is inserted into the uterus to extract cells from the fluid surrounding the fetus.
Those tests miss 8 percent of Down syndrome cases, and give false positive results about 5 percent of the time. Because amniocentesis is invasive, it bears a slight risk of causing miscarriage.
The new test misses only a very small fraction of Down syndrome cases, meaning fewer women would be recommended for amniocentesis, Bianchi said.
The test can also be administered earlier in the pregnancy, which gives doctors the opportunity for interventions aimed to improve a Down syndrome baby's cognitive function.
“We believe improving neurogenesis and cognitive behavior is an achievable goal,” Bianchi said.