While the cause of SIDS is unknown, many clinicians and researchers believe that SIDS is associated with problems in the ability of the baby to arouse from sleep, to detect low levels of oxygen, or a buildup of carbon dioxide in the blood. When babies sleep face down, they may re-breathe exhaled carbon dioxide.
Scientists in Australia have found that some babies at risk of sudden infant death syndrome, or SIDS, have low levels of an enzyme called butyrylcholinesterase (BChE) in their blood.
The rate of SIDS deaths per 100,000 live births has declined in Australia since the beginning of national public education campaigns about risk factors associated with SIDS in 1991 (AIHW 2012). Between 2007 and 2017 the rate declined from 28 per 100,000 to 6 in 2017, following a peak in 2009 of 32 per 100,000.
The potential factors that contribute to the occurrence of SIDS include inadequate prenatal care, low birth weight (<2499gr), premature infants, intrauterine growth delay, short interval between pregnancies and maternal substance use (tobacco, alcohol, opiates).
SIDS has no symptoms or warning signs. Babies who die of SIDS seem healthy before being put to bed. They show no signs of struggle and are often found in the same position as when they were placed in the bed.
SIDS is less common after 8 months of age, but parents and caregivers should continue to follow safe sleep practices to reduce the risk of SIDS and other sleep-related causes of infant death until baby's first birthday. More than 90% of all SIDS deaths occur before 6 months of age.
SIDS and Age: When Is My Baby No Longer at Risk? SIDS can occur anytime during a baby's first year of life (it's extremely rare after 1 year of age). Although the causes of SIDS are still largely unknown, doctors do know that the risk of SIDS appears to peak between 2 and 4 months of age and decreases after 6 months.
It may be because babies don't sleep as deeply when they have a pacifier, which helps wake them up if they're having trouble breathing. A pacifier also keeps the tongue forward in the mouth, so it can't block the airway.
White noise reduces the risk of SIDS.
We DO know that white noise reduces active sleep (which is the sleep state where SIDS is most likely to occur).
Dr. Hauck: We don't know for sure why room-sharing without bed-sharing is protective, but we have some theories. One is that the babies are sleeping more lightly because there is more movement around them (so they cannot get into as deep a sleep, which can contribute to the final pathway in SIDS).
Epidemiologic data suggest that SIDS is related to the sleep state, but exiguous literature has addressed infants who had been awake at the time of sudden catastrophic deterioration and subsequent death.
Breastfeeding has been shown to reduce the occurrence of SIDS by over 50 percent by improving the immune system, promoting brain growth, reducing reflux and a variety of other factors.
SIDS is most common at 2-4 months of age when the cardiorespiratory system of all infants is in rapid transition and therefore unstable. So, all infants in this age range are at risk for dysfunction of neurological control of breathing.
The highest SIDS rates in 1990 (>2.0/1000 live births) were in Ireland, New Zealand, and Scotland. More recently, the highest SIDS rates (>0.5/1000 live births) are in New Zealand and the United States.
Studies have shown that the increased SIDS risk associated with colder temperatures in the winter can be explained by excessive clothing and overwrapping of infants.
Infants who die from SIDS may have a problem with the part of the brain that helps control breathing and waking during sleep. If a baby is breathing stale air and not getting enough oxygen, the brain usually triggers the baby to wake up and cry to get more oxygen.
In most cases of sleep-related infant death, it is impossible to make a definitive classification of SIDS vs. accidental suffocation. Autopsy findings are similar and death scenes often reveal possible asphyxiating conditions, such as prone sleep or co-bedding, without clear evidence of airway obstruction.
The results showed a positive correlation between temperature and SIDS in 3–12 month-old infants specifically. On days when temperatures were greater than 29 °C, there was a 2.78 times greater chance of sudden infant death than on 20 °C days.
Although running a fan during sleep time is one way parents can provide adequate ventilation to help protect their infants from SIDS, it's not enough.
Results The majority of SIDS deaths (83%) occurred during night-time sleep, although this was often after midnight and at least four SIDS deaths occurred during every hour of the day.
Frequent night waking is thought to be protective against SIDS. Studies of near-miss infants and siblings of SIDS infants show that these babies have fewer night-waking episodes.