Editing SIDS (section)

==Risk factors==
The exact cause of SIDS is unknown.<ref name=NIH2013Cause/> Although studies have identified risk factors for SIDS, such as putting infants to bed on their bellies, there has been little understanding of the syndrome's biological process or its potential causes. Deaths from SIDS are unlikely to be due to a single cause, but rather to multiple risk factors.<ref>{{ cite book | vauthors = Byard RW | chapter = Sudden Infant Death Syndrome: Definitions |date=2018| chapter-url = http://www.ncbi.nlm.nih.gov/books/NBK513393/ | veditors = Duncan JR, Byard RW | title = SIDS Sudden Infant and Early Childhood Death: The Past, the Present and the Future |publisher=University of Adelaide Press|isbn=9781925261677|pmid=30035958|access-date=2019-08-01|archive-date=24 February 2021|archive-url=https://web.archive.org/web/20210224234544/http://www.ncbi.nlm.nih.gov/books/NBK513393/|url-status=live}}</ref> The frequency of SIDS does appear to be influenced by social, economic, or cultural factors, such as maternal education, race or ethnicity, or poverty.<ref name="pmid16254231">{{cite journal | vauthors = Pickett KE, Luo Y, Lauderdale DS | title = Widening social inequalities in risk for sudden infant death syndrome | journal = American Journal of Public Health | volume = 95 | issue = 11 | pages = 1976–1981 | date = November 2005 | pmid = 16254231 | pmc = 1449471 | doi = 10.2105/AJPH.2004.059063 }}</ref> SIDS is believed to occur when an infant with an underlying biological vulnerability, who is at a critical development age, is exposed to an external trigger.<ref name=Kin2009/> The following risk factors generally contribute either to the underlying biological vulnerability or represent an external trigger:

===Tobacco smoke===
SIDS rates are higher in babies of mothers who [[Smoking and pregnancy|smoke during pregnancy]].<ref name="sullivan"/><ref>[[Surgeon General of the United States|Office of the Surgeon General of the United States]] [http://www.surgeongeneral.gov/news/speeches/06272006a.html Report on Involuntary Exposure to Tobacco Smoke] {{webarchive|url=https://web.archive.org/web/20110806133133/http://www.surgeongeneral.gov/news/speeches/06272006a.html |date=2011-08-06 }}([http://www.surgeongeneral.gov/library/secondhandsmoke/report/fullreport.pdf PDF] {{webarchive|url=https://web.archive.org/web/20090205173605/http://www.surgeongeneral.gov/library/secondhandsmoke/report/fullreport.pdf |date=2009-02-05 }})</ref> Between no smoking and smoking one cigarette a day, on average, the risk doubles. About 22% of SIDS in the United States is related to maternal smoking.<ref>{{cite journal | vauthors = Anderson TM, Lavista Ferres JM, Ren SY, Moon RY, Goldstein RD, Ramirez JM, Mitchell EA | title = Maternal Smoking Before and During Pregnancy and the Risk of Sudden Unexpected Infant Death | journal = Pediatrics | volume = 143 | issue = 4 | pages = e20183325 | date = April 2019 | pmid = 30858347 | pmc = 6564075 | doi = 10.1542/peds.2018-3325 }}</ref> SIDS correlates with levels of [[nicotine]] and its derivatives in the baby.<ref name="Bajanowski">{{cite journal | vauthors = Bajanowski T, Brinkmann B, Mitchell EA, Vennemann MM, Leukel HW, Larsch KP, Beike J | title = Nicotine and cotinine in infants dying from sudden infant death syndrome | journal = International Journal of Legal Medicine | volume = 122 | issue = 1 | pages = 23–28 | date = January 2008 | pmid = 17285322 | doi = 10.1007/s00414-007-0155-9 | s2cid = 26325523 }}</ref> Nicotine and derivatives cause alterations in [[neurodevelopment]].<ref>{{cite journal | vauthors = Lavezzi AM, Corna MF, Matturri L | title = Ependymal alterations in sudden intrauterine unexplained death and sudden infant death syndrome: possible primary consequence of prenatal exposure to cigarette smoking | journal = Neural Development | volume = 5 | pages = 17 | date = July 2010 | pmid = 20642831 | pmc = 2919533 | doi = 10.1186/1749-8104-5-17 | doi-access = free }}</ref>

===Sleeping===
Placing an infant to sleep while lying on the belly or side rather than on the back increases the risk for SIDS.<ref name=Moon2012/><ref>{{cite journal | vauthors = Carlin RF, Moon RY | title = Risk Factors, Protective Factors, and Current Recommendations to Reduce Sudden Infant Death Syndrome: A Review | journal = JAMA Pediatrics | volume = 171 | issue = 2 | pages = 175–180 | date = February 2017 | pmid = 27918760 | doi = 10.1001/jamapediatrics.2016.3345 | s2cid = 25569308 }}</ref> This increased risk is greatest at two to three months of age.<ref name=Moon2012/> Elevated or reduced room temperature also increases the risk,<ref name=Moon2007>{{cite journal | vauthors = Moon RY, Horne RS, Hauck FR | title = Sudden infant death syndrome | journal = Lancet | volume = 370 | issue = 9598 | pages = 1578–1587 | date = November 2007 | pmid = 17980736 | doi = 10.1016/S0140-6736(07)61662-6 | url = http://adc.bmj.com/cgi/content/short/46/248/579-a | access-date = 14 February 2019 | url-status = live | s2cid = 24624496 | archive-url = https://web.archive.org/web/20210829073529/https://adc.bmj.com/content/46/248/579.2 | archive-date = 29 August 2021 | url-access = subscription }}</ref> as does excessive bedding, clothing, soft sleep surfaces, and [[stuffed animal]]s in the bed.<ref>{{cite journal | vauthors = Fleming PJ, Levine MR, Azaz Y, Wigfield R, Stewart AJ | title = Interactions between thermoregulation and the control of respiration in infants: possible relationship to sudden infant death | journal = Acta Paediatrica | volume = 82 | issue = Suppl 389 | pages = 57–59 | date = June 1993 | pmid = 8374195 | doi = 10.1111/j.1651-2227.1993.tb12878.x | s2cid = 44497216 }}</ref> [[Bumper pads]] may increase the risk of SIDS due to the risk of suffocation. They are not recommended for children under one year of age, as this risk of suffocation greatly outweighs the risk of head bumping or limbs getting stuck in the bars of the crib.<ref name=Moon2012/>

[[Co-sleeping|Sharing a bed]] with parents or siblings increases the risk for SIDS.<ref>{{cite journal | vauthors = McIntosh CG, Tonkin SL, Gunn AJ | title = What is the mechanism of sudden infant deaths associated with co-sleeping? | journal = The New Zealand Medical Journal | volume = 122 | issue = 1307 | pages = 69–75 | date = December 2009 | pmid = 20148046 }}</ref> This risk is greatest in the first three months of life, when the mattress is soft, when one or more persons share the infant's bed, especially when the bed partners are using drugs or alcohol or are smoking.<ref name=Moon2012/> The risk remains, however, even in parents who do not smoke or use drugs.<ref>{{cite journal | vauthors = Carpenter R, McGarvey C, Mitchell EA, Tappin DM, Vennemann MM, Smuk M, Carpenter JR | title = Bed sharing when parents do not smoke: is there a risk of SIDS? An individual level analysis of five major case-control studies | journal = BMJ Open | volume = 3 | issue = 5 | pages = e002299 | date = May 2013 | pmid = 23793691 | pmc = 3657670 | doi = 10.1136/bmjopen-2012-002299 }} {{open access}}</ref> The [[American Academy of Pediatrics]] thus recommends "room-sharing without bed-sharing", stating that such an arrangement can decrease the risk of SIDS by up to 50%. Furthermore, the academy has recommended against devices marketed to make bed-sharing "safe", such as "in-bed co-sleepers".<ref name=AAP2011>{{cite journal | vauthors = Moon RY | title = SIDS and other sleep-related infant deaths: expansion of recommendations for a safe infant sleeping environment | journal = Pediatrics | volume = 128 | issue = 5 | pages = 1030–1039 | date = November 2011 | pmid = 22007004 | doi = 10.1542/peds.2011-2284 | doi-access = free }}</ref>

Room sharing as opposed to solitary sleeping is known to decrease the risk of SIDS.<ref>{{cite book | vauthors = Young J, Shipstone R | chapter = Shared Sleeping Surfaces and Dangerous Sleeping Environments|date=2018| chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK513372/ | veditors = Duncan JR, Byard RW | title =SIDS Sudden Infant and Early Childhood Death: The Past, the Present and the Future|place=Adelaide (AU)|publisher=University of Adelaide Press|isbn=978-1-925261-67-7|pmid=30035939|access-date=2021-01-11|archive-date=4 November 2022|archive-url=https://web.archive.org/web/20221104162006/http://www.ncbi.nlm.nih.gov/books/NBK513372/|url-status=live}}</ref>

===Breastfeeding===
[[Breastfeeding]] is associated with a lower risk of SIDS.<ref>{{cite journal | vauthors = Hauck FR, Thompson JM, Tanabe KO, Moon RY, Vennemann MM | title = Breastfeeding and reduced risk of sudden infant death syndrome: a meta-analysis | journal = Pediatrics | volume = 128 | issue = 1 | pages = 103–110 | date = July 2011 | pmid = 21669892 | doi = 10.1542/peds.2010-3000 | doi-access = free }}</ref> It is not clear if co-sleeping among mothers who breastfeed without any other risk factors increases SIDS risk.<ref>{{cite journal | vauthors = Fleming PJ, Blair PS | title = Making informed choices on co-sleeping with your baby | journal = BMJ | volume = 350 | pages = h563 | date = February 2015 | pmid = 25643704 | doi = 10.1136/bmj.h563 | s2cid = 27309256 }}</ref>

===Pregnancy and infant factors===
SIDS rates decrease with increasing maternal age, with [[teenage pregnancy|teenage mothers]] at greatest risk.<ref name="sullivan">{{cite journal | vauthors = Sullivan FM, Barlow SM | title = Review of risk factors for sudden infant death syndrome | journal = Paediatric and Perinatal Epidemiology | volume = 15 | issue = 2 | pages = 144–200 | date = April 2001 | pmid = 11383580 | doi = 10.1046/j.1365-3016.2001.00330.x }}</ref> Delayed or inadequate [[prenatal care]] also increases risk.<ref name="sullivan"/> Low [[birth weight]] is a significant risk factor. In the United States from 1995 to 1998, the SIDS death rate for infants weighing 1000–1499 g was 2.89/1000, while for a birth weight of 3500–3999 g, it was only 0.51/1000.<ref name=wonder /><ref>{{cite journal | vauthors = Hunt CE | title = Small for gestational age infants and sudden infant death syndrome: a confluence of complex conditions | journal = Archives of Disease in Childhood. Fetal and Neonatal Edition | volume = 92 | issue = 6 | pages = F428–F429 | date = November 2007 | pmid = 17951549 | pmc = 2675383 | doi = 10.1136/adc.2006.112243 }}</ref> [[Premature birth]] increases the risk of SIDS death roughly fourfold.<ref name="sullivan"/><ref name="wonder"/> From 1995 to 1998, the U.S. SIDS rate for births at 37–39 weeks of [[gestation]] was 0.73/1000, while the SIDS rate for births at 28–31 weeks of gestation was 2.39/1000.<ref name="wonder"/>

[[Anemia]] has also been linked to SIDS<ref>{{cite journal | vauthors = Poets CF, Samuels MP, Wardrop CA, Picton-Jones E, Southall DP | title = Reduced haemoglobin levels in infants presenting with apparent life-threatening events--a retrospective investigation | journal = Acta Paediatrica | volume = 81 | issue = 4 | pages = 319–321 | date = April 1992 | pmid = 1606392 | doi = 10.1111/j.1651-2227.1992.tb12234.x | s2cid = 33298390 }}</ref> (however, per item 6 in the list of epidemiologic characteristics below, the extent of anemia cannot be evaluated at autopsy because an infant's total [[hemoglobin]] can only be measured during life).<ref>{{cite journal | vauthors = Giulian GG, Gilbert EF, Moss RL | title = Elevated fetal hemoglobin levels in sudden infant death syndrome | journal = The New England Journal of Medicine | volume = 316 | issue = 18 | pages = 1122–1126 | date = April 1987 | pmid = 2437454 | doi = 10.1056/NEJM198704303161804 }}</ref> SIDS incidence rises from zero at birth, is highest from two to four months of age, and declines toward zero after the infant's first year.<ref>{{cite journal | vauthors = Mage DT |title=A probability model for the age distribution of SIDS |journal=J Sudden Infant Death Syndrome Infant Mortal |volume=1 |pages=13–31 |year=1996}}</ref>

===Genetics===
[[Genetics]] plays a role, as SIDS is more prevalent in males.<ref name="wonderANDwho">See [http://wonder.cdc.gov CDC WONDER online database] {{webarchive|url=https://web.archive.org/web/20100424201355/http://wonder.cdc.gov/ |date=2010-04-24 }} and {{cite web |url=http://www3.who.int/whosis/menu.cfm?path=whosis,inds,mort&language=english |title=WHO Mortality Database |date=23 November 2001 |publisher=[[World Health Organization]] |access-date=2006-03-18 |archive-url=https://web.archive.org/web/20040627063703/http://www3.who.int/whosis/menu.cfm?path=whosis,inds,mort&language=english |archive-date=2004-06-27 }} for data on SIDS by gender in the US and throughout the world.</ref><ref name="Mage DT, Donner EM 2004 1210–5">{{cite journal | vauthors = Mage DT, Donner EM | title = The fifty percent male excess of infant respiratory mortality | journal = Acta Paediatrica | volume = 93 | issue = 9 | pages = 1210–1215 | date = September 2004 | pmid = 15384886 | doi = 10.1080/08035250410031305 }}</ref>  There is a consistent 50% male excess in SIDS per 1000 live births of each sex. Given a 5% male excess birth rate, there appears to be 3.15 male SIDS cases per 2 female cases, for a male fraction of 0.61.<ref name="wonderANDwho"/><ref name="Mage DT, Donner EM 2004 1210–5"/> This value of 61% in the US is an average of 57% black male SIDS, 62.2% white male SIDS, and 59.4% for all other races combined. Note that when multiracial parentage is involved, the infant's race is arbitrarily assigned to one category or the other; most often, it is chosen by the mother. The [[sex linkage|X-linkage]] hypothesis for SIDS and the male excess in infant mortality have shown that the 50% male excess might be related to a dominant X-linked [[allele]], occurring with a frequency of {{Frac|1|3}} that is protective against [[Cerebral hypoxia|transient cerebral anoxia]]. An unprotected male would occur with a frequency of {{Frac|2|3}} and an unprotected female would occur with a frequency of {{Frac|4|9}}.

About 10 to 20% of SIDS cases are believed to be due to [[channelopathies]], which are inherited defects in the [[ion channels]] that play an important role in the contraction of the heart.<ref>{{cite journal | vauthors = Behere SP, Weindling SN | title = Inherited arrhythmias: The cardiac channelopathies | journal = Annals of Pediatric Cardiology | volume = 8 | issue = 3 | pages = 210–220 | date = 2014 | pmid = 26556967 | pmc = 4608198 | doi = 10.4103/0974-2069.164695 | doi-access = free }}</ref>

Genetic evidence published in November 2020 concerning the case of [[Kathleen Folbigg]], who was imprisoned for the death of her children, showed that at least two of the children had genetic mutations in the [[CALM2]] gene that predisposed them to heart complications.<ref>{{Cite web | vauthors = de Vinuesa CG |title=Kathleen Folbigg's children likely died of natural causes, not murder. Here's the evidence my team found |url=http://theconversation.com/kathleen-folbiggs-children-likely-died-of-natural-causes-not-murder-heres-the-evidence-my-team-found-156487 |access-date=2021-12-16 |website=The Conversation |date=4 March 2021 |language=en |archive-date=4 March 2021 |archive-url=https://web.archive.org/web/20210304085909/http://theconversation.com/kathleen-folbiggs-children-likely-died-of-natural-causes-not-murder-heres-the-evidence-my-team-found-156487 |url-status=live }}</ref> Kathleen was pardoned 5 June 2023 after spending 20 years in jail.<ref>{{Cite news | vauthors = Rose T |date=2023-06-05 |title=Kathleen Folbigg pardoned and released after 20 years in jail over deaths of her four children |language=en-GB |work=The Guardian |url=https://www.theguardian.com/australia-news/2023/jun/05/kathleen-folbigg-pardoned-after-20-years-in-jail-over-deaths-of-her-four-children |access-date=2023-06-05 |issn=0261-3077}}</ref>

===Alcohol===
Drinking of alcohol by parents is linked to SIDS.<ref>{{cite journal | vauthors = Van Nguyen JM, Abenhaim HA | title = Sudden infant death syndrome: review for the obstetric care provider | journal = American Journal of Perinatology | volume = 30 | issue = 9 | pages = 703–714 | date = October 2013 | pmid = 23292938 | doi = 10.1055/s-0032-1331035 | s2cid = 25034518 }}</ref> One study found a positive correlation between the two during New Years celebrations and weekends.<ref>{{cite journal | vauthors = Phillips DP, Brewer KM, Wadensweiler P | title = Alcohol as a risk factor for sudden infant death syndrome (SIDS) | journal = Addiction | volume = 106 | issue = 3 | pages = 516–525 | date = March 2011 | pmid = 21059188 | doi = 10.1111/j.1360-0443.2010.03199.x | url = https://zenodo.org/record/886389 | access-date = 6 September 2017 | url-status = live | archive-url = https://web.archive.org/web/20170906181709/https://zenodo.org/record/886389 | archive-date = 6 September 2017 }}</ref> Another found that [[alcohol use disorder]] was linked to a more than doubling of risk.<ref>{{cite journal | vauthors = O'Leary CM, Jacoby PJ, Bartu A, D'Antoine H, Bower C | title = Maternal alcohol use and sudden infant death syndrome and infant mortality excluding SIDS | journal = Pediatrics | volume = 131 | issue = 3 | pages = e770–e778 | date = March 2013 | pmid = 23439895 | doi = 10.1542/peds.2012-1907 | s2cid = 2523083 }}</ref>

===Other===
A 2022 study found that infants who died of SIDS exhibited significantly lower specific activity of [[butyrylcholinesterase]], an enzyme involved in the brain's arousal pathway, shortly after birth. This can serve as a [[Biomarker (medicine)|biomarker]] to identify infants with a potential [[Autonomic nervous system|autonomic]] [[cholinergic]] dysfunction and elevated risk for SIDS.<ref>{{cite journal | vauthors = Harrington CT, Hafid NA, Waters KA | title = Butyrylcholinesterase is a potential biomarker for Sudden Infant Death Syndrome | journal = eBioMedicine | volume = 80 | pages = 104041 | date = June 2022 | pmid = 35533499 | pmc = 9092508 | doi = 10.1016/j.ebiom.2022.104041 | s2cid = 248645079 }}</ref><ref>{{Cite web |title=Researchers Pinpoint Reason Infants Die From SIDS |url=https://www.biospace.com/article/researchers-answer-how-and-why-infants-die-from-sids/ |access-date=2022-05-12 |website=BioSpace |language=en-US |archive-date=10 May 2022 |archive-url=https://web.archive.org/web/20220510182628/https://www.biospace.com/article/researchers-answer-how-and-why-infants-die-from-sids/ |url-status=live }}</ref><ref>{{cite news |title=Groundbreaking New Study Finds Possible Explanation for SIDS |url=https://www.goodnewsnetwork.org/groundbreaking-new-study-finds-possible-explanation-for-sids/ |agency=Goods News Network |publisher=Goods News Network |date=May 17, 2022 |access-date=20 May 2022 |archive-date=22 May 2022 |archive-url=https://web.archive.org/web/20220522123206/https://www.goodnewsnetwork.org/groundbreaking-new-study-finds-possible-explanation-for-sids/ |url-status=live }}</ref>

SIDS has been linked to cold weather, with this association believed to be due to over-bundling and thus, overheating.<ref>{{cite web |title=NIH alerts caregivers to increase in SIDS risk during cold weather |url=https://www.nih.gov/news-events/news-releases/nih-alerts-caregivers-increase-sids-risk-during-cold-weather |website=National Institutes of Health (NIH) |access-date=27 July 2018 |language=en |date=3 September 2015 |archive-date=10 April 2019 |archive-url=https://web.archive.org/web/20190410154310/https://www.nih.gov/news-events/news-releases/nih-alerts-caregivers-increase-sids-risk-during-cold-weather |url-status=live }}</ref> Premature babies are at four times the risk of SIDS, possibly related to an underdeveloped ability to automatically control the cardiovascular system.<ref>{{cite journal | vauthors = Horne RS | title = Effects of prematurity on heart rate control: implications for sudden infant death syndrome | journal = Expert Review of Cardiovascular Therapy | volume = 4 | issue = 3 | pages = 335–343 | date = May 2006 | pmid = 16716094 | doi = 10.1586/14779072.4.3.335 | s2cid = 26689292 }}</ref>

A 2-part edition of ''[[The Cook Report]]'' from 1994 claimed that antimony- and phosphorus-containing compounds used as fire retardants in [[PVC]] and other cot mattress materials were a cause of SIDS. Subsequent investigation by an Expert Panel led by Lady Limerick found that there was no evidence to support this claim.<ref>See [https://web.archive.org/web/20001026033455/http://www.sids.org.uk/fsid/limerick.htm FSID Press release].</ref> The report also states that toxic gas cannot be generated from antimony in mattresses and that babies had SIDS on mattresses that did not contain the compound.

It has been suggested that some cases of SIDS may be related to ''[[Staphylococcus aureus]]'' and ''[[Escherichia coli]]'' infections.<ref>{{cite journal | vauthors = Weber MA, Klein NJ, Hartley JC, Lock PE, Malone M, Sebire NJ | title = Infection and sudden unexpected death in infancy: a systematic retrospective case review | journal = Lancet | volume = 371 | issue = 9627 | pages = 1848–1853 | date = May 2008 | pmid = 18514728 | doi = 10.1016/S0140-6736(08)60798-9 | s2cid = 8017934 }}</ref>