Sudden Infant Death Syndrome (... Health Article

Sudden Infant Death Syndrome (SIDS)

Also referred to as crib death or cot death.

The sudden, unexpected death of a seemingly normal, healthy infant under one year of age that remains unexplained after a thorough postmortem investigation, including an autopsy and a review of the case history.

In the United States, sudden infant death syndroms (SIDS) is the leading cause of postneonatal deaths (those occurring between the ages of 28 days and one year). According to the National Center for Health Statistics, at least 4,000 infants in the United States die of SIDS every year, or 1.03 per 1,000 live births. (In the late 1990s, many sources placed the annual total number of deaths as high as 6,000 due to possible under-reporting.) Ninety percent of SIDS deaths occur during the first six months of life, mostly between the ages of two and four months. SIDS also occurs about 1.5 times more frequently in boys than girls.

Understanding SIDS

Studies have identified many risk factors for SIDS, but the actual cause of the disorder remains a mystery. Although investigators are still not sure whether the immediate cause of SIDS deaths is respiratory failure or cardiac arrest, patterns of infant sleep, breathing, and arousal are a major focus of current research. It is known that young infants often stop breathing for short periods of time, then gasp and start again. Some researchers and physicians believe that SIDS involves a flaw in the mechanism, perhaps controlled by the central nervous system, that is responsible for re-starting breathing. Aside from its occurrence during sleep, the other most striking feature of SIDS is its narrow age distribution, which has prompted researchers to examine the developmental changes that take place during this period, especially between the ages of two and four months, when most SIDS deaths occur. A growing number of experts believe that rather than a single cause, there are a number of different conditions that can cause or contribute to SIDS. This picture is complicated still further by the interaction of possible physical abnormalities with a number of environmental and developmental factors known to increase the risk of SIDS. Premature infants, and low birth weight babies generally, are known to be at increased risk of developing SIDS, as are infants born to teenage mothers, poor mothers, and mothers who for any reason have had inadequate prenatal care. Other risk factors include maternal smoking during pregnancy, exposure to smoking in the home after birth, formula feeding rather than breastfeeding, and prior death of a sibling from SIDS (although this is thought to be due to shared environmental risk factors rather than genetic predisposition). The rate of SIDS in African American infants is twice as high as that of Caucasians, a fact attributed to the lower quality of prenatal care received by many African American mothers. Many SIDS deaths occur in babies who have recently had colds (a possible reason that SIDS is most prevalent in winter—the time when upper respiratory infections are most frequent).