Labor Stage, ThirdPlacenta, RetainedPlacenta AccretaLabor, ObstetricPlacentaUmbilical VeinsUmbilical ArteriesHernia, UmbilicalFetal BloodHuman Umbilical Vein Endothelial CellsUmbilicusEndothelium, VascularPregnancyCord Blood Stem Cell TransplantationAnxiety, SeparationCell SeparationCells, CulturedUltrasonography, PrenatalImmunomagnetic SeparationEndothelial CellsChromatography, High Pressure LiquidInfant, Newborn