Umbilical Venous D-dimer Concentrations With and Without Labor

Abstract

In Brief Objective To determine if labor activates the fetal fibrinolytic system. Methods A total of 59 umbilical venous blood samples were collecting following vaginal delivery at term (n = 20), cesarean delivery following labor at term (n = 12), vaginal delivery before term (n = 18), and cesarean delivery without labor (n = 9). D-dimer concentrations, a sensitive marker of fibrinolysis, were measured by enzyme-linked immunosorbent assay, and compared between groups by Kruskel-Wallis and Mann Whitney U tests, with significance defined as P < .05. Results There were no significant differences in median D-dimer concentrations between newborns delivered vaginally or by cesarean after term labor or preterm labor. There were significant differences in median umbilical venous D-dimer concentrations in subjects delivered vaginally or by cesarean after term or preterm labor compared with term subjects without labor delivered by cesarean (427, 773, and 326 versus 87 ng/mL, P = .01) Conclusion Elevation of umbilical plasma D-dimer concentrations in laboring patients suggests activation of fetal fibrinolysis before delivery. Fetal fibrinolysis, as reflected by umbilical venous D-dimer concentrations, is activated at birth following labor but not following elective cesarean delivery.