Quantitative Analysis Of Cell-free Fetal DNA In Maternal Plasma At Different Pregnant Conditions

Objective: Measure mean concentration of cell-free fetal DNA in maternal plasma at different pregnant conditions . Address the mean concentration and 95% confidence interval for parameter at different pregnant conditions .Methods: Cell-free fetal DNA was isolated from maternal plasma , SRY gene on the Y chromosome was measured by real-time Fluorescence Quantitative Polymerase Chain-reaction (FQ-PCR).Results: Qualitative analysis of PCR : 32 cases were detected SRY gene out of 38 cases at early pregnant carrying male fetuses, the last 62 cases at late pregnant carrying male fetuses were all detected SRY gene . Quantitative analysis of PCR : Cell-free Fetal DNA is present in high concentrations in maternal plasma, reaching a mean and 95% confidence interval for parameter: 149.25Eq/ml, 33.28~265.22 Eq/ml; 212.14Eq/ml, 142.76~281.52 Eq/ml and 678.70Eq/ml, 595.01~726.40 Eq/ml in early normal pregnancy , in late normal pregnancy and in late abnormal pregnancy respectively. The concentrations of cell-free fetal DNA are higher in late gestation than in early gestation, about 1.4-times (LSD-t, p<0.01).The media circulating cell-free fetal DNA was increased 3.9-fold in 30 pre-eclamptic women compared with 32 control pregnant women( LSD-t, p<0.01).Conclusions: 1: Cell-free fetal DNA in maternal plasma can be detected as early as 48 days of gestation. 2: The number of cell-free fetal DNA in maternal plasma increases with gestational age. 3: Cell-free fetal DNA, we found an overall 3.9-fold increase in women with pre-eclampsia compared with control pregnancies. 4: Cell-free fetal DNA in maternal plasma is of great value in the non-invasive prenatal diagnosis.