by Donna Brezinski, MD, Director of Newborn Medicine, Anna Jaques Hospital

The death of an infant is a tragedy unimaginable to most of us, yet for every 100,000 births in the United States more than 50 seemingly healthy infants will succumb to Sudden Infant Death Syndrome (SIDS). Another 20 infants per 100,000 will die unexpectedly from causes such as accidental suffocation. Since the "Back to Sleep" campaign was initiated by the American Academy of Pediatrics in 1992 promoting placing infants on their backs rather than their stomachs to sleep, we have seen the rate of SIDS decrease by about half, but there has been no significant decline in SIDS rate for several years. Additionally we have seen an increase in other causes of unexpected infant death. This may be in part due to better classification of SIDS such that we are no longer grouping accidental suffocation into the same category as SIDS. However, it does illustrate that, in addition to true SIDS, accidental death also is a significant threat to the newborn.

Sudden Infant Death Syndrome is defined as the death of an infant less than one year of age that remains unexplained after thorough examination event including autopsy, examination of the death scene and assessment of the infant's medical history. There appears to be a moderately higher incidence of SIDS in male infants. There are also ethnic differences in incidence, with SIDS occurring more than twice as often in African-American and Native American infants as compared to white, Hispanic and Asian infants.

There does not appear to be a single cause of SIDS. A more recent hypothesis is the "triple risk model" which states that SIDS can occur when the following three conditions exist: a vulnerable infant, a critical period of development in that infant, and an exogenous stressor.

What makes an infant vulnerable to SIDS? Unfortunately, we are not able to identify every vulnerable infant in advance since they appear healthy prior to succumbing to SIDS. However, we do know that some infants with certain prenatal conditions have increased risk. For example, infants born to mothers who smoke and/or consume alcohol during their pregnancy are at increased risk for SIDS. It has been suggested by some scientists studying SIDS that there may a neurodevelopmental effect of these substances on the fetus that ultimately makes them more vulnerable. Additionally, preterm infants are a vulnerable population having a SIDS rate more than double that of term infants.

The most common time for SIDS to occur in term infants is between 2 and 4 months of age, and about 90% of SIDS cases occur before 6 months of age. In preterm infants, the peak incidence of SIDS is several weeks later than in term infants. For the many infants this time period defines a critical period of development, which, when combined with other factors, may increase likelihood of SIDS.

There have been many outside influences, or exogenous stressors, that have been strongly associated with increased risk for SIDS. We already are well aware of the association of SIDS risk with placing an infant on his or her stomach to sleep. Even placing an infant on the side rather than the back increases the risk of SIDS. Other things associated with increased risk include overheating the infant by overdressing, maternal smoking, having an infant share a bed with a caregiver who is overtired or under the influence of drugs, medications or alcohol, and multiple persons sharing a bed with an infant.

With our increased knowledge of SIDS and SIDS risk, we now know that there are strategies we can adopt to further reduce an infant's chance of dying unexpectedly. While the "Back to Sleep Program" addressed the important risk factor of sleep position and, as a result, has no doubt saved many infant lives, we can expand our efforts to further reduce risk. At Anna Jaques Hospital we have adopted a "Safe Sleep" Campaign which focuses on addressing a number of risk factors and interventions important for SIDS prevention. Our teaching points spell out the word "SLEEP":

Safest place is in a crib with no loose bedding
Lay baby to sleep on the back - ALWAYS!
Eliminate cigarettes and alcohol
Educate secondary caregivers
Pacifiers reduce risk

We also strongly promote breastfeeding, which in addition to the many well known benefits to mother and baby, also has been shown to reduce risk of SIDS. Use of a pacifier has been shown to have a strong protective effect in SIDS prevention in multiple studies, but the American Academy of Pediatrics recommends that if choosing to use a pacifier it should not be introduced until after one month of age in breastfeeding mothers.

We all hope to see further progress in the area of SIDS prevention. Taking the time to learn these important facts and interventions could save a baby's life.