Conditions in which there is poor blood flow to the systemic circulation, such as coarctation of the aorta suggests that the body does not receive the oxygenated blood it requires with resultant cyanosis.The five most common cyanotic heart defects that may result in Blue Baby Syndrome include the following:

Methemoglobinemia
Methemoglobinemia which can be acquired or congenital, occurs when the iron in hemoglobin is oxidized from Fe2+ to Fe3+, leading to poor binding of oxygen. Additionally, the oxygen that is already bound is held more tightly to the hemoglobin due to a higher affinity, resulting in less oxygen delivery. A methemoglobin level >1.5g/dL causes cyanosis. The most common congenital cause is a deficiency in the enzyme cytochrome b5 reductase which reduces methemoglobin in the blood. However, in infants the most common cause of methemoglobinemia is acquired through the ingestion of nitrates through well water or foods. Infants younger than 4 months are at greater risk given that they drink more water per body weight, they have a lower NADH- cytochrome b5 reductase activity, and they have a higher level of fetal hemoglobin which converts more easily to methemoglobin. Additionally, infants are at an increased risk after an episode of gastroenteritis due to the production of nitrites by bacteria. The sources of nitrate can include fertilizers used in agricultural lands, waste dumps or pit latrines. For example, nitrate levels are subject to monitoring to comply with drinking water quality standards in the United States and other countries.
Screening for critical congenital heart defect should be done on all newborns after 24hours or shortly before discharge. Oxygen saturation is measured in the right hand and either foot.A screening is considered positive if:

Oxygen saturation <90% in either extremity,
Oxygen saturation 90-94% in both extremities on 3 measurements separated by an hour each,
Oxygen saturation difference >3% between both extremities on 3 measurements separated by an hour each. Management
Treatment for blue baby syndrome will depend on the underlying cause. When evaluating a patient for cyanosis or respiratory distress, vital signs should be monitored, especially the patients heart rate and oxygen saturation. It is beneficial to have vascular access established. In newborns, the pulse oximeter is typically placed on the right hand to determine pre-ductal oxygenation, referring to oxygenation before the ductus arteriosus (connection between aorta and pulmonary artery). This gives the oxygenation level the heart and brain receive. Traditionally, supplemental oxygen is given in an escalating manner beginning with free-flowing oxygen, progressing to positive pressure ventilation or continuous positive airway pressure, and ending with mechanical intubation. The goal oxygen saturation is between 85 and 95%. If an infant requires supplemental oxygen for a prolonged time it should be heated and humidified to avoid heat loss. Cyanotic heart disease
Some babies born with cyanotic heart disease are treated with prostaglandin E1 after birth to keep the ductus arteriosus open and allow for more oxygenated blood to be pumped to the body. Many also receive oxygen therapy to increase the percentage of oxygen in the blood.