Interesting! "Blue Baby" used to describe the lack of closure of the foramen ovale in the heart septum of a newborn that mixed oxygenated and non-oxygenated blood. Venous blood has a decidedly blue color that caused the infant to appear blue in color rather than the healthy pink color that is imparted by arterial (oxygenated) blood. With the advent of heart surgery to close the defect, infants with this problem now survive and thrive.