What is SIDS

CC-BY Daniel Rothamel
CC-BY Daniel Rothamel

Sudden Infant Death Syndrome (SIDS) is a sudden and unexpected death of an infant of age below 12 months (the maximum of SIDS incidences occurs between 2nd and 4th months of child’s age). SIDS is the most common cause of infants’ deaths in first world countries and occurs roughly once per 10000-20000 births.

SIDS is a complex syndrome and it is assumed to be a result of endogenous and exogenous factors (Trachtenberg et al, 2012). It is diagnosed by exclusion – all other causes of infant’s death are excluded systematically according to a special protocol. As we gather more knowledge about diseases and syndromes of young age, the protocol is systematically updated (one of the latest updates are covered by Jensen et al, 2012). The most common SIDS risk factors are: male gender, low birth weight, improper sleep position, tobacco smoke exposition, infection, heat stress or co-sleeping with parents. However, these risk factors cover so many infants, that they cannot be used to predict the risk of SIDS incidence.

For some time it was popular to use home cardiomonitors or respiratory monitors, but quickly it was shown that sleep apnea happens to perfectly healthy children. In a large research on effectiveness of home cardiomonitors it was shown that these apparatuses alarmed parents of more than 40% of monitored infants (Ramanathan R et al, 2001), which means their specificity was three orders of magnitude below level of SIDS occurences (40% vs less than 0.1%). Current guidelines do not recommend using home cardiomonitors and respiratory monitors as a means of preventing SIDS (AAP, 2011), unless there is a recommendation from a physician.

The only major effect so far of SIDS research was a campaign „Back to Sleep” that ran in early nineties. Parents were advised to put their babies to sleep on their back. These recommendations are thought to be responsible to lower the number of SIDS incidences by 50% after 1990 (Ponsonby et al, 2002).. However, since then, the statistics of sudden infrant death syndrome did not improve (Trachtenberg et al, 2012) – according to CDC, in the US only, there are 2500 SIDS incidences per year.

Despite over 10 thousands of research papers on the topic (according to PubMed database), SIDS mechanism is still a mystery. Other than general recommendations for parents and day-care units, there is no diagnostic procedure that would help in assessing the risk of sudden infant death syndrome.


AAP (2011) SIDS and Other Sleep-Related Infant Deaths: Expansion of Recommendations for a Safe Infant Sleeping Environment. Pediatrics: peds.2011–2284

Jensen LL, Rohde MC, Banner J & Byard RW (2012) Reclassification of SIDS cases—a need for adjustment of the San Diego classification? Int. J. Legal Med. 126: 271–277

Ponsonby A-L, Dwyer T & Cochrane J (2002) Population trends in sudden infant death syndrome. Semin. Perinatol. 26: 296–305

Ramanathan R, Corwin MJ, Hunt CE & et al (2001) Cardiorespiratory events recorded on home monitors: Comparison of healthy infants with those at increased risk for sids. JAMA 285: 2199–2207

Trachtenberg FL, Haas EA, Kinney HC, Stanley C & Krous HF (2012) Risk factor changes for sudden infant death syndrome after initiation of Back-to-Sleep campaign. Pediatrics 129: 630–638