Sudden Infant Death Syndrome also known as SIDS was defined in 1969 as the sudden death of an infant under the age of one, which after thorough investigation fails to present a cause of death. It is only determined to be SIDS after an investigation of the scene of death is done, a clinical history and an autopsy. SIDS is a death of exclusion because researchers are unclear about the causes. Researchers now believe that infants who die of SIDS are born with one or more conditions that make them vulnerable to both internal and external stresses that occur in the normal life of an infant. It most often occurs quickly in the night to seemingly healthy infants between the ages of two to four months and during the fall and winter months. SIDS occurs more often in boys than girls, with a sixty to forty percent ratio. African American and American Indian infants are two to three times more likely to die from SIDS than other children however government agencies are making efforts to reach these populations with information about SIDS. .
Between 1983 and 1992 the average number of SIDS deaths reported was five to six thousand a year. Since the mid 1990's those averages have dropped considerably. In 1992 The American Academy of Pediatrics announced that infants should sleep on their backs to reduce the risk of SIDS. Beginning that year the number of SIDS related deaths began to decline. In 1994 the "Back to Sleep" campaign began. The campaign stated that the safest way for an infant to sleep was to lay him or her on their backs, research showed that side and stomach sleeping babies were more likely to die from SIDS than babies that slept on their backs. In the year 2000 only 2,523 infants died from SIDS, half of what they have been in recent years, however it is still the leading cause of deaths in infants under one year of age. Although SIDS occurs in every race a higher percent occurs in African American and American Indian infants and the lowest percent in Hispanics and Asians.