Sudden Infant Death Syndrome (SIDS)
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- Leading cause of death in infants 1–12 months of age
- Third leading cause of infant mortality overall
- SIDS deaths have been reduced by >50% in the US and other countries that have introduced risk-reduction campaigns, heavily focused on back sleeping for infants (1).
- The condition still remains mysterious, and the exact cause is unknown.
- The sudden death of an infant <1 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
- Sudden infant death syndrome (SIDS) was first formally defined in 1969. The definition was revised in 1989.
- System(s) affected: Cardiovascular; Endocrine/Metabolic; Nervous; Pulmonary
- Synonym(s): Crib death; Cot death
- SIDS can affect any infant, but some infants are at higher risk than others, including African Americans and American Indians/Native Americans, males, infants whose mothers smoked/used illegal drugs during pregnancy, and several others described below.
- There is a characteristic age pattern, with deaths peaking at 2–4 months, and more deaths occurring during the colder seasons.
- For 2008: All races: 0.55/1,000 live births (2,350 cases/yr):
- White non-Hispanic: 0.55/1,000 live births (1,238 cases/yr)
- African American non-Hispanic: 1.07/1,000 live births (665 cases/yr)
- Hispanic: 0.32/1,000 live births (328 cases/yr)
- Native American: 0.91/1,000 live births (45 cases/yr)
- Asian/Pacific Islander: 0.23/1,000 live births (59 cases/yr)
- Predominant age: Uncommon in 1st month of life; peak occurs between 2 and 4 months of age; 90% of deaths occur by 6 months of age.
- Predominant sex: Male > Female (52–60% male)
Occurs only in infants
- Although some infants may die from SIDS who have no apparent risk factors, most have ≥1 of the following risk factors associated with SIDS:
- Race: African Americans and Native Americans have highest incidence.
- Season: Late fall and winter months
- Time of day: Between midnight and 6 A.M.
- Activity: During sleep
- Low birth weight; intrauterine growth retardation (IUGR)
- Maternal factors:
- Younger age
- Decreased education
- Maternal use of cigarettes/drugs (e.g., cocaine, opiates) during pregnancy
- Higher parity
- Inadequate prenatal care
- Respiratory/GI infection in recent past
- Sleep practices:
- Prone and side sleep positions
- Overheating from heavy clothing and bedding and/or elevated room temperature
- Soft bedding
- Bed sharing
- No room sharing
- Passive cigarette smoke exposure after birth
- No pacifier use
- No breastfeeding
Emerging evidence for genetic risk factors, especially related to impaired brain-stem regulation of breathing or other autonomic control, impaired immune responses, and cardiac ion channelopathies associated with long QT syndrome and fatal arrhythmia
- Maternal avoidance of cigarette smoking and illicit drug use during pregnancy
- Avoidance of passive cigarette smoke exposure
- Avoidance of the prone (face-down) and side sleep positions, excessive bed clothing, and soft bedding such as pillows, comforters, and bumper pads or a soft mattress
- Avoidance of overheating
- A crib, bassinet, or cradle conforming to federal safety standards is the recommended sleeping location.
- Avoidance of bed sharing with the infant, particularly by adults other than the parent(s) or by other children. Bed sharing should be avoided if the mother/father has used cigarettes, drugs, or alcohol. Bed sharing on couches is very dangerous and should never be done.
- Infants who sleep in the same room as their parents (without bed sharing) have a lower risk of SIDS. It is recommended that infants sleep in a crib/bassinet in their parents' bedroom, which when placed close to their bed will allow for more convenient breastfeeding and contact.
- Breastfeeding is associated with a decreased risk of SIDS and is recommended for all infants (3)[B].
- Pacifier use is associated with a reduced risk of SIDS:
- Consider offering a pacifier at bedtime and nap time.
- Delay the introduction of the pacifier among breast-fed infants until 1 month of age (4)[B].
- Pacifier use has not been found to be detrimental to breastfeeding if it is introduced after the baby is 1 month of age, when breastfeeding is well established (5)[A].
- Avoidance of commercial devices marketed to reduce the risk of SIDS
- It is critical that all people caring for infants, including daycare providers, be instructed in these risk-reduction measures.
- Newborn nurseries should implement these recommendations well before discharge so parents see appropriate practices modeled.
Strong evidence for a respiratory pathway that includes the following stages:
- A life-threatening event causes severe asphyxia and/or brain hypoperfusion. This can include rebreathing exhaled carbon dioxide in a face-down position.
- The vulnerable infant does not wake up or turn his/her head in response to asphyxia, resulting in further rebreathing and inability to recover from apnea.
- Progressive apnea leads to hypoxic coma.
- Bradycardia and hypoxic apnea occur.
- Autoresuscitation fails, resulting in prolonged apnea and death (6).
- There are many theories. There may be subtle developmental abnormalities resulting from pre- and/or perinatal brain injury, which make the infant vulnerable to SIDS.
- Possible causes:
- Abnormalities in respiratory control and arousal responsiveness
- Central and peripheral nervous system abnormalities
- Cardiac arrhythmias
- Rebreathing in face-down position on soft surface, leading to hypoxia and hypercarbia
- SIDS may occur when ≥1 environmental risk factors interact with ≥1 genetic risk factors.
Commonly Associated Conditions
Infants are generally well, or may have had a mild febrile illness (i.e., gastroenteritis or an upper respiratory infection) prior to death.