Infants born with congenital heart defects turn blue and such babies are ‘blue babies’. It occurs when the blood carried to the body contains, a less than normal amount of oxygen due to congenital heart defects. The most common defect is a hole in the septum separating two ventricles (ventricular septal defect – VSD). Normally, deoxygenated blood returns from the body to right atrium from where it flows to the right ventricle. From the right ventricle deoxygenated blood flows to the lungs where it is oxygenated.
The oxygenated blood from the lungs flows to the left atrium then to the left ventricle from where it is distributed to all parts of the body. In the case of VSD, deoxygenated blood instead of flowing to the lungs from the right ventricle, flows to the left ventricle (through the septal hole) from where is distributed to the body parts. Deoxygenated blood causes the body to turn blue (oxygenated blood is red). Blue baby disease was discovered by an American cardiologist, Hellen Brooke Taussig (1898-1986).
Infants who are fed on milk containing water contaminated with high ,nitrate content turn blue and is commonly referred to as ‘Blue baby syndrome’ (BBS). The skin of infants turn blue when there is insufficient oxygen supply to the body through the blood. Nitrates reduce the oxygen carrying capacity of haemoglobin present in the red blood corpuscles (RBC). Infants of less than six months of age are more prone to BBS. Their haemoglobin has poor chemical equilibrium and hence restoration of haemoglobin cannot take place as quickly as in adults.