Pregnancy induces a series of changes in the womans physiology, including hemostasis. The aim of this study was to determine plasma and amniotic vWF concentrations before and following delivery, as well as to compare them with umbilical blood levels and control group values. The study group comprised 34 pregnant women in reference to a control group of healthy women of similar age. Concentrations were measured immunoenzymatically (ELISA). Mean vWf:Ag plasma levels prior to delivery amounted to 263% SD 157. Following delivery they increased to 296% SD 189. The amniotic fluid concentrations oscillated between 0% and 50%. Levels of vWf:Ag in the umbilical plasma were similar to those of the control group reaching 112%, SD27. We observed a correlation between the weight of the afterbirth and maternal vWf:Ag levels. Thus, the placental endothelium might be an important source of maternal circulating vWf.

Keywords: delivery, Pregnancy, von Willebrand Factor