Quantitative detection of cell-free fetal DNA in peripheral blood of pregnant women during early pregnancy

Objective: This study aimed for the quantitative detection of cell-free fetal DNA (cffDNA) in peripheral plasma of pregnant women, which provides basic data for clinical non-invasive prenatal screening in early pregnancy. Materials and Methods: A total of 243 individuals with gestational age of 5-10(+6) weeks were selected for this study, who required abortion. mDNA was extracted from villi, and Y-chromosome specific SRY gene was detected by nested PCR, which was regarded as standard for quantitative detection of accuracy. CffDNA was extracted from peripheral blood and SRY gene's expression was detected by real-time fluorescent quantitative PCR. Results: Among 243 cases, nested PCR detected 163 individuals with SRY gene positive, and 80 were negative. Out of 163, in 140 cases SRY was detected in cffDNA, but 23 cases with gestational age 5-6 + 6 weeks were negative. However at 7th week of pregnancy, it was also detected in those 23 cases. The average concentration of cff DNA in 10th week of pregnancy was found significantly higher than in 7th, 8th, and 9th week of pregnancy. Conclusion: Thus, this study indicates the efficiency and reliability of cffDNA in peripheral blood of 7-10th week of gestational period for the detection of early pregnancy.