Introduction. The physiological task of the blood coagulation system during childbirth is to prevent excessive blood loss.Aim: to evaluate the quantitative and qualitative characteristics in the system P-selectin-von Willebrand factor (vWF)-metallo-protease ADAMTS13 during natural and uncomplicated childbirth in women with a physiological pregnancy.Materials and methods. The study included 40 pregnant women without somatic pathology, with a physiologically progressing pregnancy that ended with physiological birth (general group). Of these, 16 women had their first birth (group 1), 18 had their second birth (group 2) and 6 had their third birth (group 3). Venous blood sampling was performed at three points throughout the study: 1st point — the onset of labor, 2nd point — 2 hours after childbirth and 3rd point — 24 hours after child -birth. The control group consisted of 25 healthy non-pregnant women. The blood samples were examined for: vWF antigen (vWF:Ag), binding ability of vWF to platelet receptor GPIb (vWF:GPIb), binding ability of vWF to collagen type I (vWF:CBAI) and type III (vWF:CBAIII), antigen and activity ADAMTS13 (ADAMTS13:Ag and ADAMTS13:AC), antibodies to ADAMTS13 (ADAMTS13:AB) and P-selectin.Results. The medians of the studied vWF characteristics in the genera l group were statistically significantly higher compared to the control group at all study points, with the exception of the medians of the vWF:GPIb/vWF:Ag ratio, which in the general group were statistically significantly lower at all study points when compared with the control group. The median values of vWF:GPIb and vWF:Ag in women in the second group were statistically significantly higher at all points of the study, compared with similar indicators in both the first and third groups. The median values of ADAMTS13:AC and ADAMTS13:AB in the overall group were statistically significantly higher when compared with the control group at all study points. Median ADAMTS13:Ag and ADAMTS13:AC/ADAMTS13:Ag ratios were statistically significantly lower at all study points. Individual P-selectin values varied widely from 212.1 to 1398 ng/ml, but the medians of this indicator were statistically significantly higher in all study groups and at all study points compared to the control group.Conclusion. The increase in platelet-binding and collagen-binding abilities of vWF suggests that these adhesive properties of the hemostatic protein play an important role in preventing excessive bleeding during labor. Taking into account the decrease in the vWF:GPIb/vWF:Ag ratio compared to the control group, the adhesion of vWF to collagen is more important under these conditions. Despite the fact that ADAMTS13 concentration does not decrease, an actual twofold increase in its activity provides a sufficient antithrombotic effect. The interaction between vWF and ADAMTS13 under conditions of physiological labor does not lead to excessive formation and accumulation of high-affinity antibodies to ADAMTS13.
