Table 2.

Size distribution of total and fetal circulatory DNA in maternal plasma samples obtained early in pregnancy.1

Size of DNA fraction, kbMedian (range)
Size distribution of total DNA, %Size distribution of fetal DNA, %Proportion of fetal DNA per fraction, %
<0.326.985.528.4
(12.7–41.3)(67.8–100.0)(11.6–56.6)
0.3–0.529.111.74.0
(26.1–54.4)(0.0–15.5)(0.0–13.5)
0.5–1.028.51.20.4 (0.0–5.2)
(14.5–25.9)(0.0–16.8)
1.0–1.58.20.00.0
(4.5–12.1)
1.5–238.60.00.0
(7.6–23.7)
  • 1 Eight samples were analyzed in this study. Median gestational age was 13 + 2 weeks. Size distributions of total circulatory DNA, circulatory fetal DNA, and the proportion of fetal DNA were determined as described in the footnotes for Table 1 .