A Study On The Correlation Between The Fetal DNA In Maternal Blood, Cervix Length And Premature Delivery

Objective: Explore the correlation between the cell-free fetal DNA inmaternal blood, the cervix length and the premature delivery.Methods: 60 cases, bearing a male fetus by B-ultrasonic(also confirmed afterdelivery.), of premature delivery and the cured threatened premature deliveryin the hospital were selected as two control group (A,B)by differentgestationsl age and 60cases, bearing a male fetus by B-ultrasonic(alsoconfirmed after delivery.), of normal pregnancy as two contrast group(A,B)by different gestational age. The gestational ages of the two groups haveno significant difference. SRY levels in maternal blood were quantified withPCR (QF-PCR), the concentration of fetal DNA with SRY gene therein beingmeasured; the cervix length was measured with JILANTAIMAGEPOINT. Thedifference of the concentration of fetal DNA and the cervix length betweenthe two groups were compared using variance analysis and Q test.Results: In-group comparison: the fetal DNA concentration of 30 prematuredelivery cases ranges from A (n=10): 286.3-2562.2 copy/ml, with mean645.5±54.4 copy/ml;B(n=20):307.3-2683.1copy/ml, with mean709.9±61.3copy/ml while the other 30 cured threatened premature delivery cases rangesfrom group A(n=20): 192.3-1595.6copy/ml, with mean 231.4±51.5copy/ml,group B: 189.3-1595.6copy/ml, with mean 249.9±43.8copy/ml, Varianceanalysis and Chi-Square test: group A;X~2=1.0750, p=0.5863; group B:X~2=1.0680, p=0.5933 Q test indicates that the fetal DNA concentration of thethreatened premature delivery is significantly higher than that of thecontrast group, and the premature delivery significantly higher than the threatened premature delivery (at p＜0.01). The mean cervix length ofpremature delivery group A is 25.8±5.7mm, group B is 24.8±5.3mm, thethreatened premature delivery groupA is38.8±4.7mm, group B is 37.9±4.1mmand the normal pregnancy group A is38.2±3.8mm, group B is36.2±4.3mm. Thedifference both in group A and B between premature delivery cases andthreatened premature delivery cases and between the premature delivery casesand the normal pregnant cases is very significant at P＜0.01; however, thedifference between the normal pregnant cases and the threatened prematuredelivery cases is not significant at P＞0.05. Negative relation was observedbetween the fetal DNA concentration and the mean cervix length(group A r=-0.653, p＜0.01, group B r=-0.639, p＜0.01).Conclusion: The concentration of the cell-free fetal DNA in maternal bloodand the cervix length is highly correlated with the premature delivery.