Sudden Infant Death Syndrome (SIDS)

By studying large groups of young infants, a few of whom eventually go on to die of SIDS, scientists have found certain factors that occur more frequently in sudden death victims. For example, a genetic defect in an enzyme involved in fatty acid metabolism has been identified as a possible cause of death in a small percentage of SIDS victims. With this defect, the infant's brain can become starved for energy and the baby enters a coma. Italian researchers have demonstrated a link between a particular type of irregular heartbeat and SIDS. Infants who inherit this irregularity, called "long QT syndrome," are 41 times more likely to die of SIDS. This syndrome also is a leading cause of sudden death in adults. It is possible to screen for this irregularity with heart monitors and to treat it with drugs.

Babies born prematurely are at greater risk for SIDS. So are twins and triplets. A twin is more than twice as likely as a non-twin to die of SIDS. Boys are more susceptible than girls. Formula-fed infants are more susceptible than breast-fed babies. SIDS also is more common in the babies of mothers who are poor, under 20 years old, have other children, and receive little medical care during pregnancy. Mothers who smoke during pregnancy and the presence of cigarette smoke in the home after birth also increases the likelihood of SIDS. Other proposed risk factors including childhood vaccines and allergies to cow's milk have failed to show any link to SIDS.

It is important to remember that more than twothirds of SIDS cases occur in babies without known risk factors. Some scientists believe that all infants are potential victims if certain factors in their bodies and their environment interact in a particular unknown way. By studying risk factors researchers hope to gain important insights into the causes of the syndrome.

In general, SIDS does not appear to be hereditary. Siblings of SIDS victims have only a slightly higher risk of sudden death compared to the average population. Yet some parents who have a subsequent baby after suffering the loss of a baby to SIDS find it very reassuring to use a home monitor. Attached to the baby, this machine sounds an alarm if the baby's respiration or heart rate drops below normal. The National Institutes of Health has stated that home monitors have not been shown to prevent SIDS.