Effect of labor on plasma concentrations and postpartum clearance of cell-free, pregnancy-associated, placenta-specific microRNAs

Objective: This study aimed to investigate the effect of labor on plasma concentrations of cell-free, pregnancy-associated, placenta-specific microRNAs (miRNAs) before and after delivery.

Method: In the non-labor group (32 women), cesarean section (C/S) was performed before the beginning of labor. In the labor group (32 women), C/S was performed after the beginning of labor. Plasma concentrations of cell-free, pregnancy-associated, placenta-specific miRNAs (miR-515-3p, miR-517a, miR-517c, and miR-518b) were measured by real-time quantitative PCR. Each miRNA concentration was compared between the non-labor and labor groups.

Results: Before C/S, plasma concentrations of cell-free, pregnancy-associated, placenta-specific miRNAs in the labor group were significantly higher than those in the non-labor group (P = 0.001 for 515-3p, P = 0.002 for 517a, P = 0.001 for 517c, and P = 0.003 for 518b). Twenty-four hours after delivery, plasma concentrations of cell-free, pregnancy-associated, placenta-specific miRNAs in the labor group were significantly higher than those in the non-labor group (P = 0.002 for 515-3p, P = 0.017 for 517a, P = 0.043 for 517c, and P = 0.009 for 518b).

Conclusion: The presence of labor affects cell-free, pregnancy-associated, placenta-specific miRNA levels in maternal plasma. Labor also affects postpartum clearance of these miRNAs 24 h after delivery.