Prenatal DNA testing has been a fiercely competitive market of late. Yet another company entered the fray recently when Natera, a start-up based in San Carlos, California, announced the 1 March launch date of a commercial test that can detect chromosomal abnormalities in the developing fetus from just a drop of an expectant mother's blood—with a sensitivity it claims is on par with that of more invasive techniques such as amniocentesis and chorionic villus sampling, both of which carry an elevated risk of miscarriage.

Natera now joins three other California-based firms—Sequenom, Verinata Health (a division of sequencing giant Illumina) and Ariosa Diagnostics—in offering such products for women at high risk of having babies with Down's syndrome or other chromosomal irregularities known as aneuploidies. With US health insurers, including Aetna and Wellpoint, saying they plan to cover the new tests, the market for DNA-based prenatal screening now provides “a billion dollar opportunity,” according to David Ferreiro, an analyst at Oppenheimer & Co. in Boston.

Nature Medicine looks at how the four tests stack up.

Table 1 Analyzing aneuploidies: A survey of genomic prenatal test offerings.
Full size table