Background: circulating maternal plasma fetal nucleic acid discovery opens up new possibilities for noninvasive prenatal diagnosis. Small molecule RNA (miRNAs) are a class of small RNA, a recent in-depth investigation, because of their important role in regulating gene expression. Placental origin of the nucleic acid is released into the maternal plasma, we assume that produced by the placenta miRNA will be released into the maternal plasma.

Methods: We systematically searched the placenta in pregnant women plasma miRNA compared to high concentrations of placental tissue and maternal blood cells and investigation of this novel class of stability and filtration pregnancy maternal plasma markers to identify miRNA.

Results: in a panel of TaqMan MicroRNA Assays perfect 157 miRNA occurred at concentrations> 10 times more than in maternal blood cells detected in the placenta and postpartum maternal plasma. These placental miRNA (miR-141 of miR-149 and miR-299-5p and miR-135B) 4 most abundant in maternal plasma was detected in plasma during pregnancy and the postpartum detection rate decreases. The increase in the plasma concentration of miR-141 in pregnancy to progress to the third trimester of pregnancy. [Compared with the mRNA encoded CSH1 Chorionic somatomammotropin hormone 1 (placental lactogen)], miR-141, maternal plasma is more stable, and after filtration, the concentration is not decreased.

Conclusions: We have demonstrated the presence of the placenta in pregnant women plasma miRNA, and provide some stability and physical properties. These findings open a new class of molecular markers to pregnancy monitoring.