The single umbilical artery.
D001741:Black or African American; D000013:Congenital Abnormalities / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D014469:Umbilical Arteries / Q000002:abnormalities*; D014481:United States; D044465:White People