Quantitative Detection Of Fetal DNA In Maternal Plasma And Its Clinical Significance In The Prediction Of Parturient Period And Preterm Labor

Objective: To detect the content of fetal DNA (fDNA)in maternal plasma in the late pregnancy, the parturient period and preterm labor, and to explore the content variation of fDNA in maternal plasma in these pregnant women and its clinical significance in the prediction of labor and preterm labor.Methods: DYS14 gene located on Y chromosome was amplified by using the real-time fluorescence quantitative PCR (RQ-PCR) technique in maternal blood plasma of 30 cases in 28- 42 weeks of gestation, 10 in parturient period and 30 in preterm labor. Preterm labor group can be divided into three groups according to the etiological factors, which were pregnancy induced hypertension (10 cases), premature rupture of membrane (10 cases) and polyhydramnios (10 cases). CT values of DYS14 gene were analyzed quantitatively, and the contents of fDNA in each group were determined and compared by RQ-PCR.Result:①All plasma samples of pregnancies with male fetuses can be detected precisely by RQ-PCR.②The contents of maternal fDNA were 233.8±69.7 GE/mL in 28-31 weeks, 488.6±55.4 GE/mL in 32-35 weeks, 896.7±70.6 GE/mL in 36-42 weeks and 1168.8±77.3GE/mL in parturient period respectively. There are significant differences in the contents of maternal fDNA among each group of late pregnancy and parturient period group (P<0.01). Furthermore, the contents of maternal fDNA reached the highest level in parturient period.③The contents of fDNA in spontaneous preterm labor were 1188.6±57.7 GE/mL, and there are no significance in the contents of maternal fDNA between parturient period groups and labor groups (P>0.05).④The contents of fDNA in preterm labor group were 1122.5～1549.3 GE/mL in pregnancy induced hypertension, 989.8～1206.5 GE/mL in premature rupture of membrane, 1066.5～1454.3 GE/mL in polyhydramnios respectively. There are no significance in the contents of maternal fDNA between two groups in preterm labor group (P>0.05), but when each group compared with normal late pregnancy in the same gestation age respectively, their differences are significances (P<0.01).Conclusion: The contents of fDNA in maternal plasma rised accordingly, with the increasing of the gestation age, and reached the highest level in parturient period. The results suggest that the rise of fDNA in maternal plasma might be one of the motivation of labor. The fDNA in maternal plasma in preterm labor was obviously higher than that in its normal gestation. The contents of fDNA in maternal plasma can be an predictive indicator for preterm labor. RQ-PCR is a sensitive, rapid and precise method in detecting the contents of fetal DNA in maternal plasma.