Sudden infant death syndrome is marked by the sudden death of an infant that is unexpected by medical history, and remains unexplained after a thorough forensic autopsy and a detailed death scene investigation. An infant is at the highest risk for SIDS during sleep, which is why it is sometimes referred to by the terms cot death or crib death.
Over the past decades, it has become increasingly apparent that assignment of the cause and manner of death in cases of SUDI is critically dependent upon careful investigation and reconstruction of death scenes and evaluation of the circumstances of death. With this recognition, it is not surprising that improved death scene investigations have added uncertainty and resulted in a diagnostic shift away from SIDS towards other causes of death, such as positional asphyxia or undetermined. Nevertheless, death scene investigations are still all too often incomplete and lack of information continues to hamper evaluation of the real circumstances of death further contributing to confusion.
Combining the results, the researchers found that the rate of SIDS was 60 percent lower among infants who had any amount of breastfeeding compared to those who didn't breastfeed, and more than 70 percent lower in infants that been breastfed exclusively - without any formula - for any period of time. That led the authors to conclude that any breastfeeding helps protect a baby against sudden death.
Frothy fluid escaping from the nose and mouth is seen in about half of infants who die from SIDS. Postmortem hypostatic staining as an indicator of position has assumed increased importance since prone sleeping has been shown to be a major risk factor for SIDS. Evidence of sweat in clothing suggests overwrapping. Internal examination shows subserosal petechial haemorrhages in the thymus in most cases. These may be related to age and are commoner in babies dying of SIDS than in controls.
Two senior paediatric pathologists say they have discovered vitamin D deficiency in a significant number of children who have died of Sudden Infant Death Syndrome. The doctors say that vitamin D deficiency and associated diseases such as the bone disease rickets could potentially explain deaths and injuries that are often thought to be suspicious.
This analysis found that pacifier use when an infant is placed for sleep has a significant protective effect against SIDS. This conclusion is supported even further by a recent report from a California study that found a 90% reduced risk of SIDS among pacifier users during last sleep compared with control infants
The AAP issued a policy statement in 2005 discouraging bed sharing, noting that almost one half of infants who die from SIDS in the United States do so while sleeping with parents. Bed sharing carries a substantially increased risk in low–birth-weight infants and in children of smokers and persons who use illicit drugs or alcohol. Recent analyses have suggested that the risks of bed sharing are isolated to infants younger than four months, with no significant increase in risk for older infants.
SIDS usually occurs during sleep and is the most common cause of death in the postneonatal period (from 28 to 364 days of life). The risk is greatest for infants aged between one and four months, for those with a low birth weight, and during the colder seasons. Although the usual age range given is two weeks to two years, a similar syndrome is sometimes seen in older children and adults.
In 2006, 2,323 infants died from SIDS, accounting for 8.1 percent of all infant deaths. SIDS is the third leading cause of infant death in the United States. The death rate in 2006 was 54.5 per 100,000 live births. Caucasians, African Americans, and American Indians/Alaska Natives all have SIDS death rates greater than the national rate. In contrast, Asian Americans/Pacific Islanders and Hispanics have death rates below the national rate.
It is currently believed that many mechanisms contribute to SIDS. A leading hypothesis maintains that many of these infants have an immature or abnormal arousal response. Postmortem examinations of the brainstems of infants dying of SIDS have revealed hypoplasia or decreased neurotransmitter binding of the arcuate nucleus. Infants possessing this abnormality may be uniquely prone to central and cardiorespiratory depression resulting from hyperthermia, hypercarbia and hypoxemia during sleep. Death ensues due to failure of the arousal mechanism.
Attitudes towards the risk factors have changed and refined in the past two decades. Besides premature low birth weight, exposure to nicotine, overheating and prone sleeping position are considered to be the most significant risk factors. The significance of the latter one seems to be born out by the success of the so called 'back to sleep' campaigns.