Sudden Infant Death Syndrome (SIDS) is a rare but devastating occurrence, striking infants almost exclusively between the ages of 2 and 4 months. It is defined as “the sudden death of an infant under one year of age that remains unexplained after a thorough case investigation, including performance of a complete autopsy; examination of the death scene; and review of the clinical history.” It is characterized by the sudden cessation of breathing without cause in a sleeping infant.

Approximately 6,000 infants died each year from SIDS before 1993; this decreased to about 4,000 in 1995, due largely to the effectiveness of the “Back to Sleep” campaign begun in 1992. After reviewing published data linking the prone (face down) sleeping position and SIDS, the American Academy of Pediatricians (AAP) recommended that infants be placed down to sleep on their backs (supine) or on their sides, rather than the traditional practice of placing them in the prone position. It was noted that while the side position was safer than the prone position, the supine position was the safest. Infants sleeping on their sides were twice as likely to die from SIDS as supine infants, and prone infants were 10 times more likely to die from SIDS than those in a supine position. The campaign was very effective in changing habits: Studies later revealed that while 70 percent of parents put babies to bed in the prone position in 1992, only 30 percent did so by 1995. (Interestingly, the prone position might be safer for certain infants, including premature infants with respiratory distress, infants with significant gastroesophageal reflux and infants with certain airway abnormalities.)

Despite decades of study, the cause of SIDS remains unknown. There are, however, several known risk factors. Of these, sleeping position, sleeping on soft bedding and exposure to cigarette smoke are the most significant. In fact, cigarette smoking by the mother while pregnant, or by any household member during infancy, tripled the risk of SIDS. Infants sleeping on soft bedding have a four-fold higher risk of SIDS. Other less significant risk factors include bottle-feeding, overdressing, male sex, a history of prematurity and low birth weight, low socioeconomic status and environmental pollution. Still, the majority of deaths that are due to SIDS occur in healthy infants and are unpredictable.