The single umbilical artery.
D000015:Abnormalities, Multiple / Q000209:etiology; D005260:Female; D005313:Fetal Death / Q000209:etiology; D006330:Heart Defects, Congenital / Q000209:etiology; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007231:Infant, Newborn; D011247:Pregnancy; D044469:Racial Groups; D013997:Time Factors; D014469:Umbilical Arteries / Q000002:abnormalities*; D014564:Urogenital Abnormalities