Macones GA. Helping providers interpret cell-free fetal DNA testing (editorial). Am J Obstet Gynecol 2015;213:2.

An editorial in the July 2015 issue contains a mathematical error. A sentence in the second paragraph, lines 14-16, reads: “Using the calculator, the PPV for this result is 38%, which means in fact that there is a 52% chance that the fetus is not affected by Down syndrome.” The second percentage should have been 62%.