Maternal plasma cell-free DNA in the prediction of preeclampsia

Objectives: To examine whether maternal plasma concentration of total cell-free (cf) DNA and fetal fraction at 11-13 and 20-24 weeks’ gestation in pregnancies that subsequently develop preeclampsia (PE) is different from those without this complication.

Methods: Total cfDNA and fetal fraction were measured in 20 cases of early-PE, requiring delivery <34 weeks, 20 of late-PE with delivery >34 weeks and 200 normotensive controls, at 11-13 and 20-24 weeks’ gestation. Total cfDNA and fetal fraction measured at 11-13 weeks were converted to multiples of median (MoM), corrected for maternal characteristics and gestational age. The distributions of total cfDNA and fetal fraction at 20-24 weeks were expressed as MoM of values at 11-13 weeks. Mann-Whitney U test was used to determine the significance of differences in the median values in each outcome group to that in the controls.

Results: In the early-PE group at 11-13 weeks, compared to controls, there was a significant increase in median total cfDNA (2,104 GE/mL vs. 1,590 GE/mL) and decrease in median fetal fraction (6.8% vs. 8.7%). In the late-PE group at 20-24 weeks, compared to controls, there was a significant decrease in median fetal fraction (8.2% vs. 9.6%). These significant differences between groups were not observed when the values were converted to MoM.

Conclusion: Measurements of total cfDNA and fetal fraction in maternal plasma at 11-13 and 20-24 weeks are not predictive of PE.