Umbilical ArteriesUmbilical VeinsUltrasonography, PrenatalFetusPregnancyUltrasonography, DopplerBlood Flow VelocityHernia, UmbilicalFetal BloodHuman Umbilical Vein Endothelial CellsUmbilicusEndothelium, VascularCord Blood Stem Cell TransplantationCells, CulturedEndothelial CellsInfant, NewbornSingle Umbilical ArteryGestational AgeFetal Growth RetardationPlacental CirculationUrachal CystPlacentaHeart Rate, FetalFetal DiseasesMaternal-Fetal ExchangeFetal DistressFetal HypoxiaBlood BanksWharton JellyCell AdhesionNeovascularization, PhysiologicPulsatile FlowEndothelium