Figure 2.

Mean differences in fetal fraction according to cfDNA concentration (ng/μl). Model 1: Crude model. Model 2 was adjusted for GA and BMI. Model 3 added the average cfDNA size to Model 2. Model 4 added maternal age, multiple gestations, library concentration, and uniquely mapped reads to Model 2. Model 5 added the average cfDNA size to Model 4. Compared to Models 2 and 4, Models 3 and 5 included additional adjustments for confounding factors of average cfDNA size, and they showed significantly reduced fetal fractions across cfDNA concentration categories.