Blue baby syndrome, also known as simply blue baby, is a term used to describe infants with cyanosis, or blue-tinted skin. The condition develops when the organs, cells and tissues do not receive adequate oxygen, and the blood flowing through the body is blue in color instead of red, indicating poor oxygen levels. Although blue baby syndrome can be fatal if left untreated, modern treatments can typically correct the problem. The syndrome occurs most frequently in infants under six months of age, but it can also affect older children and adults in rare cases.

The most common cause of blue baby syndrome is Tetralogy of Fallot, a congenital heart disease in which four different abnormalities of the heart cause a reduction in blood oxygen. These abnormalities include ventricular septal defect (VSD), pulmonary stenosis, thickening of the right ventricle and a displaced or deviated aorta. VSD is characterized by a hole in the wall of the two lower chambers of the heart. Pulmonary stenosis occurs when the pulmonic valve and the muscular area below the valve are narrower than normal.

Blue baby syndrome may also be caused by excessive nitrates in drinking water. When consumed, the nitrates are converted to nitrite in the digestive system. The nitrites then react with the hemoglobin, causing dangerously high levels of methemoglobin. This enzyme cannot carry oxygen through the blood as hemoglobin does, resulting in organs, cells and tissues that are deprived of oxygen and skin with the characteristic bluish-tint. Rural areas where high levels of nitrates are present in the ground water often produce higher numbers of infants born with this condition.

Other causes of blue baby syndrome are also related to congenital heart problems. Transposition of the great arteries (TGA) occurs when the aorta and pulmonary artery are transposed or switched, causing oxygen-poor blood to be carried throughout the body instead of being sent to the lungs. Hypoplastic left heart syndrome (HLHS) can also result in blue baby syndrome, and is caused when the left side of the heart is underdeveloped, resulting in a left ventricle that does not pump enough oxygen-rich blood through the body.

Blue-tinted skin may be difficult to recognize in children with darker skin colors, but there are other symptoms to alert parents and doctors to a potential problem. The other symptoms of blue baby syndrome include fatigue, low tolerance for exercise, rapid breathing and shortness of breath, difficulty breathing or eating, and heart murmurs. The child may also fail to gain weight and appear lethargic for no apparent reason.

Treatments for blue baby syndrome depend on the cause and severity of the condition. The problem is typically evident just after birth and doctors will work quickly to correct any defect contributing to the syndrome. If the symptoms become apparent later, the infant should be taken to a pediatric cardiac center as quickly as possible, as a serious heart defect is usually the culprit. Medication may be prescribed to manage the symptoms, but in most cases heart surgery will be required to fix the underlying cause of the disorder.