Structural Malformations Defects in the face, mouth, chest wall, diaphragm, heart, and major blood vessels may lead to respiratory problems in an infant. Great care in feeding and positioning and possible correction by surgery are indicated. This occurs in about 2 infants out of 1,000. SIDS infants are usually 2 to 4 months old. The syndrome is rarely seen after the age of 6 months.
Boys die more often than girls, and there are fewer cases in the summer.
Although significant numbers of SIDS infants have low birth weights, maternal smoking is now recognized as a greater risk factor. Genetic factors have not been demonstrated, but there is a tendency for SIDS to occur multiple times in families. Other risk factors may include a young, unmarried mother and insufficient prenatal care. The relationship between these apparently life-threatening events and actual SIDS cases is uncertain. At present, a disturbance of normal sleep patterns and a combination of biochemical and neurological abnormalities or immaturity of cardiorespiratory control are the focal points of most research.