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Sudden infant death syndrome

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Title: Sudden infant death syndrome  
Author: World Heritage Encyclopedia
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Subject: Munchausen syndrome by proxy, Smoking and pregnancy, Safe to Sleep, Infant mortality, Prosecutor's fallacy
Collection: Ailments of Unknown Etiology, Causes of Death, Death of Children, Infancy, Pediatrics, Rtt
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Sudden infant death syndrome

Sudden Infant Death Syndrome
Safe Sleep logo
Safe to Sleep Public Education Campaign, NICHD
Classification and external resources
ICD-10 R95
ICD-9 798.0
OMIM 272120
DiseasesDB 12633
MedlinePlus 001566
eMedicine emerg/407 ped/2171
MeSH D013398

Sudden infant death syndrome (SIDS) also known as cot death or crib death is the sudden death of an infant that is not predicted by medical history and remains unexplained after a thorough forensic autopsy and detailed death scene investigation.[1] Infants are at the highest risk for SIDS during sleep. Typically the infant is found dead after having been put to bed, and exhibits no signs of having struggled.[2] The cause of SIDS is unknown, but some characteristics associated with the syndrome have been identified and appear to interact with other characteristics: A triple-risk model states that SIDS occurs when an infant with an underlying, biological vulnerability who is at a critical developmental age is exposed to an external trigger.[3] SIDS prevention strategies include: putting the infant to sleep on their back, a firm mattress separate from but close to caregivers, no loose bedding, a relatively cool sleeping environment, using a pacifier, and avoiding exposure to tobacco smoke.[4] The "Safe to Sleep" campaign is considered a significant public health success, credited with leading to a measurable reduction in SIDS rates.[5] SIDS was the third leading cause of infant mortality in the U.S. in 2011 and rates have been declining since 1988.[6]

Infanticide and child abuse cases may be misdiagnosed as SIDS due to lack of evidence, and caretakers of infants with SIDS are sometimes falsely accused.[7][8] Accidental suffocations are also sometimes misdiagnosed as SIDS and vice versa.[9] Grief support for families impacted by SIDS is particularly important because the death of the infant is typically sudden, without witnesses, and requires an investigation.[3]


  • Definition 1
  • Risk factors 2
    • Tobacco smoke 2.1
    • Sleeping 2.2
    • Pregnancy and infant factors 2.3
    • Genetics 2.4
    • Critical developmental age 2.5
    • Other 2.6
  • Differential diagnosis 3
  • Prevention 4
    • Sleep positioning 4.1
    • Pacifiers 4.2
    • Bedding 4.3
    • Sleep sacks 4.4
  • Management 5
  • Epidemiology 6
    • Race 6.1
  • Society and culture 7
  • See also 8
  • References 9
  • Further reading 10
  • External links 11


SIDS is a diagnosis of exclusion and should be applied to only those cases in which an infant's death is sudden and unexpected, and remains unexplained after the performance of an adequate postmortem investigation, including:

  1. an autopsy (by an experienced pediatric pathologist, if possible);
  2. investigation of the death scene and circumstances of the death;
  3. exploration of the medical history of the infant and family.

After investigation, some of these infant deaths are found to be caused by accidental suffocation, hyperthermia or hypothermia, neglect or some other defined cause.[10]

Australia and New Zealand are shifting to the term "sudden unexpected death in infancy" (SUDI) for professional, scientific, and coronial clarity.

The term SUDI is now often used instead of sudden infant death syndrome (SIDS) because some coroners prefer to use the term 'undetermined' for a death previously considered to be SIDS. This change is causing diagnostic shift in the mortality data.[11]
In addition, the U.S. Centers for Disease Control and Prevention (CDC) has recently proposed that such deaths be called "sudden unexpected infant deaths" (SUID) and that SIDS is a subset of SUID.[12]

Risk factors

The cause of SIDS is unknown. Although studies have identified risk factors for SIDS, such as putting infants to bed on their stomachs, there has been little understanding of the syndrome's biological process or its potential causes. The frequency of SIDS does appear to be influenced by social, economic, and cultural factors, such as maternal education, race or ethnicity, and poverty.[13] 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.[3] The following risk factors generally contribute either to the underlying biological vulnerability or represent an external trigger:

Tobacco smoke

Exposure to nicotine from parental smoking — SIDS rates are higher for infants of mothers who smoke during pregnancy.[14][15][16]


Placing an infant to sleep while lying on the stomach or the side increases the risk.[4] This increased risk is greatest at two to three months of age.[4] Elevated or reduced room temperature also increases the risk,[17] as does excessive bedding, clothing, soft sleep surfaces, and stuffed animals.[18] Bumper pads may increase the risk and as there is little evidence of benefit from their use; they are not recommended.[4]

Sharing a bed with parents or siblings increases the risk for SIDS.[19] 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.[4] The risk remains, however, even in parents who do not smoke or use drugs.[20] 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 recommended against devices marketed to make bed-sharing "safe", such as in-bed co-sleepers.[21]

Pregnancy and infant factors

Maternal age — SIDS rates decrease with increasing maternal age, with teenage mothers at greatest risk.[14] Delayed or inadequate prenatal care[14] Low birth weight — in the United States from 1995 to 1998, the SIDS death rate for infants weighing 1000–1499 g was 2.89/1000; for a birth weight of 3500–3999 g, it was only 0.51/1000.[22][23] Premature birth— increases risk of SIDS death roughly fourfold.[14][22] From 1995 to 1998, the U.S. SIDS rate for births at 37–39 weeks of gestation was 0.73/1000; the SIDS rate for births at 28–31 weeks of gestation was 2.39/1000.[22] A lack of breastfeeding is linked to SIDS.[24]

Anemia has also been linked to SIDS[25] (note, however, that per item 6 in the list of epidemiologic characteristics below, extent of anemia cannot be evaluated at autopsy because an infant's total hemoglobin can only be measured during life.[26]). Age of infant — 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.[27] Male sex — male children have a ~50% higher risk of SIDS than female children.[28]


Genetics plays a role, as SIDS is more prevalent in males.[29][30] 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, for a male fraction of 0.61.[29][30] 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, infant "race" is arbitrarily assigned to one category or the other; most often it is chosen by the mother. The X-linkage hypothesis for SIDS and the male excess in infant mortality have shown that the 50% male excess could be related to a dominant X-linked allele, occurring with a frequency of 13 that is protective of transient cerebral anoxia. An unprotected XY male would occur with a frequency of 23 and an unprotected XX female would occur with a frequency of 49.

Critical developmental age

The unique signature characteristic of SIDS is its 4-parameter lognormal age distribution that spares infants shortly after birth — the time of maximal risk for almost all other causes of non-trauma infant death.

By definition, SIDS deaths occur under the age of one year, with the peak incidence occurring when the infant is at 2 to 4 months of age. This is considered a critical period because the infant's ability to arouse from sleep is not yet mature.[3]


There is a tentative link with Staphylococcus aureus and Escherichia coli.[31] Vaccination does not increase the risk of SIDS, and may reduce the risk slightly.[32][33]

A 1998 report found "no evidence to substantiate the toxic gas hypothesis that antimony- and phosphorus-containing compounds used as fire retardants in PVC and other cot mattress materials are a cause of SIDS. Neither was there any evidence to believe that these chemicals could pose any other health risk to infants."[34] The report also states that "in normal cot-like conditions it is not possible to generate toxic gas from antimony in mattresses" and that "babies have also been found to die on wrapped mattresses."

A set of risk factors SIDS has been identified with: seasonality: winter maximum, summer minimum; increasing SIDS rate with live birth order; low increased risk of SIDS in subsequent siblings of SIDS; apparent life-threatening events (ALTE) are not a risk factor for subsequent SIDS; SIDS risk is greatest during sleep.[35]

Differential diagnosis

Some conditions that are often undiagnosed and could be confused with or comorbid with SIDS include:

For example, an infant with MCAD deficiency could have died by "classical SIDS" if found swaddled and prone with head covered in an overheated room where parents were smoking. Genes indicating susceptibility to MCAD and Long QT syndrome do not protect an infant from dying of classical SIDS. Therefore, presence of a susceptibility gene, such as for MCAD, means the infant may have died either from SIDS or from MCAD deficiency. It is currently impossible for the pathologist to distinguish between them.

A 2010 study looked at 554 autopsies of infants in North Carolina that listed SIDS as the cause of death, and suggested that many of these deaths may have been due to accidental suffocation. The study found that 69% of autopsies listed other possible risk factors that could have led to death, such us unsafe bedding or sleeping with adults.[43]

Several instances of infanticide have been uncovered where the diagnosis was originally SIDS.[7][8] Estimate of the percentage of SIDS deaths that are actually infanticide vary from less than 1% to up to 5% of cases.[44]

Some have underestimated the risk of two SIDS deaths occurring in the same family and the Royal Statistical Society issued a media release refuting this expert testimony in one UK case in which the conviction was subsequently overturned.[45]


A number of measures have been found to be effective in preventing SIDS including: sleeping position, breastfeeding, limiting soft bedding, immunizing the infant and the use of pacifiers.[4] The use of electronic monitors has not been found to be useful and are thus not recommended.[4] Evidence regarding fans and swaddling is unclear.[4]

Sleep positioning

A plot of SIDS rate from 1988 to 2006

Sleeping on the back has been found to reduce the risk of SIDS.[46] It is thus recommended by the American Academy of Pediatrics and promoted as a best practice by the US National Institute of Child Health and Human Development (NICHD) "Safe to Sleep" campaign. The incidence of SIDS has fallen in a number of countries in which this recommendation has been widely adopted.[47] Sleeping on the back does not appear to increase the risk of choking even in those with gastroesophageal reflux disease.[4] While infants in this position may sleep more lightly this is not harmful.[4] Sharing the same room as one's parents but in a different bed may decrease the risk by half.[4]


The use of pacifiers appears to decrease the risk of SIDS although the way they do this is unclear.[4] The American Academy of Pediatrics considers pacifier use to prevent SIDS to be reasonable.[4] Pacifiers do not appear to affect breastfeeding in the first four months, even though this is a common misconception.[48]


Product safety experts advise against using pillows, overly soft mattresses, sleep positioners, bumper pads, stuffed animals, or fluffy bedding in the crib and recommend instead dressing the child warmly and keeping the crib "naked."[49]

Blankets should not be placed over an infant's head. It has been recommended that infants should be covered only up to their chest with their arms exposed. This reduces the chance of the infant shifting the blanket over his or her head.

Sleep sacks

In colder environments where bedding is required to maintain a baby's body temperature, the use of a "baby sleep bag" or "sleep sack" is becoming more popular. This is a soft bag with holes for the baby's arms and head. A zipper allows the bag to be closed around the baby. A study published in the European Journal of Pediatrics in August 1998[50] has shown the protective effects of a sleep sack as reducing the incidence of turning from back to front during sleep, reinforcing putting a baby to sleep on its back for placement into the sleep sack and preventing bedding from coming up over the face which leads to increased temperature and carbon dioxide rebreathing. They conclude in their study "The use of a sleeping-sack should be particularly promoted for infants with a low birth weight." The American Academy of Pediatrics also recommends them as a type of bedding that warms the baby without covering its head.[51]


Families who are impacted by SIDS should be offered emotional support and grief counseling.[52] The experience and manifestation of grief at the loss of an infant is impacted by cultural and individual differences.[53]


Globally SIDS resulted in about 22,000 deaths as of 2010, down from 30,000 deaths in 1990.[54] Rates vary significantly by population from 0.05 per 1000 in Hong Kong to 6.7 per 1000 in American Indians.[55]

SIDS was responsible for 0.54 deaths per 1,000 live births in the US in 2005.[22] It is responsible for far fewer deaths than congenital disorders and disorders related to short gestation, though it is the leading cause of death in healthy infants after one month of age.

SIDS deaths in the US decreased from 4,895 in 1992 to 2,247 in 2004.[56] But, during a similar time period, 1989 to 2004, SIDS being listed as the cause of death for sudden infant death (SID) decreased from 80% to 55%.[56] According to John Kattwinkel, chairman of the Centers for Disease Control and Prevention (CDC) Special Task Force on SIDS "A lot of us are concerned that the rate (of SIDS) isn't decreasing significantly, but that a lot of it is just code shifting".[56]

Rates of SIDS by race/ethnicity in the U.S., 2009, CDC, 2013


In 2013, there are persistent disparities in SIDS deaths among racial and ethnic groups in the U.S. In 2009, the rates of death range from 20.3 for Asian/Pacific Islander to 119.2 for American Indians/Alaska Native. Rates are per 100,000 live births and enable more accurate comparison across groups of different total population size.

Research suggests that factors which contribute more directly to SIDS risk—maternal age, exposure to smoking, safe sleep practices, etc. -- vary by racial and ethnic group and therefore risk exposure also varies by these groups.[3] Cultural factors can be protective as well as problematic.[57]

Society and culture

Much of the media portrayal of infants shows them in non-recommended sleeping positions.[4]

See also


  1. ^ "Centers for Disease Control and Prevention, Sudden Infant Death". Retrieved March 13, 2013. 
  2. ^ Randall B (1996). "Witnessed sudden infant death syndrome". Journal of Sudden Infant Death Syndrome and Infant Mortality 1: 55–57. 
  3. ^ a b c d e Kinney HC, Thach BT (2009). "The sudden infant death syndrome". N. Engl. J. Med. 361 (8): 795–805.  
  4. ^ a b c d e f g h i j k l m n Moon RY, Fu L (July 2012). "Sudden infant death syndrome: an update.". Pediatrics in review / American Academy of Pediatrics 33 (7): 314–20.  
  5. ^ "Fig 4. Meta-analysis of studies examining the relationship of a pacifier used during the last sleep in SIDS victims versus controls".  
  6. ^ Hoyert DL, Xu JQ (2012). "Deaths: Preliminary data for 2011". National vital statistics reports. (National Center for Health Statistics) 61 (6): 8. 
  7. ^ a b Glatt, John (2000). Cradle of Death: A Shocking True Story of a Mother, Multiple Murder, and SIDS. Macmillan.  
  8. ^ a b Havill, Adrian (2002). While Innocents Slept: A Story of Revenge, Murder, and SIDS. Macmillan.  
  9. ^ Krous HF (June 2012). "A commentary on changing infant death rates and a plea to use sudden infant death syndrome as a cause of death". Forensic Sci Med Pathol 9 (1): 91–3.  
  10. ^ "Centers for Disease Control and Prevention, Sudden Unexpected Infant Death and Sudden Infant Death Syndrome". Retrieved March 14, 2013. 
  11. ^ NZ Ministry of Health
  12. ^
  13. ^ Pickett, KE, Luo, Y, Lauderdale, DS. Widening Social Inequalities in Risk for Sudden Infant Death Syndrome. Am J Public Health 2005;94(11):1976-1981. doi:10.2105/AJPH.2004.059063
  14. ^ a b c d Sullivan FM, Barlow SM (2001). "Review of risk factors for Sudden Infant Death Syndrome". Paediatric Perinatal Epidemiology 15 (2): 144–200.  
  15. ^ Lavezzi AM, Corna MF, Matturri L (July 2010). "Ependymal alterations in sudden intrauterine unexplained death and sudden infant death syndrome: possible primary consequence of prenatal exposure to cigarette smoking". Neural Dev 19 (5): 17.  
  16. ^ Office of the Surgeon General of the United States Report on Involuntary Exposure to Tobacco Smoke(PDF)
  17. ^ Moon RY, Horne RS, Hauck FR (November 2007). "Sudden infant death syndrome". Lancet 370 (9598): 1578–87.  
  18. ^ Fleming PJ, Levine MR, Azaz Y, Wigfield R, Stewart AJ (June 1993). "Interactions between thermoregulation and the control of respiration in infants: possible relationship to sudden infant death". Acta Paediatr Suppl 82 (Suppl 389): 57–9.  
  19. ^ McIntosh CG, Tonkin SL, Gunn AJ (2009). "What is the mechanism of sudden infant deaths associated with co-sleeping?". N. Z. Med. J. 122 (1307): 69–75.  
  20. ^ Carpenter R, McGarvey C, Mitchell EA, Tappin DM, Vennemann MM, Smuk M, Carpenter JR (2013). "Bed sharing when parents do not smoke: is there a risk of SIDS? An individual level analysis of five major case-control studies.". BMJ open 3 (5).  
  21. ^ Moon RY (November 2011). "SIDS and other sleep-related infant deaths: expansion of recommendations for a safe infant sleeping environment.". Pediatrics 128 (5): 1030–9.  
  22. ^ a b c d CDC WONDER online database
  23. ^ Hunt CE (November 2007). "Small for gestational age infants and sudden infant death syndrome: a confluence of complex conditions". Arch. Dis. Child. Fetal Neonatal Ed. 92 (6): F428–9.  
  24. ^ Hauck FR, Thompson JM, Tanabe KO, Moon RY, Vennemann MM (July 2011). "Breastfeeding and Reduced Risk of Sudden Infant Death Syndrome: A Meta-analysis". Pediatrics 128 (1): e103–10.  
  25. ^ Poets CF, Samuels MP, Wardrop CA, Picton-Jones E, Southall DP (April 1992). "Reduced haemoglobin levels in infants presenting with apparent life-threatening events—a retrospective investigation". Acta Paediatr. 81 (4): 319–21.  
  26. ^ Giulian GG, Gilbert EF, Moss RL (April 1987). "Elevated fetal hemoglobin levels in sudden infant death syndrome". N Engl J Med 316 (18): 1122–6.  
  27. ^ Mage DT (1996). "A probability model for the age distribution of SIDS". J Sudden Infant Death Syndrome Infant Mortal 1: 13–31. 
  28. ^ Mage DT, Donner M. A genetic basis for the sudden infant death syndrome sex ratio, Med Hypotheses 1997;48:137-142.
  29. ^ a b See CDC WONDER online database and,inds,mort&language=english for data on SIDS by gender in the US and throughout the world.
  30. ^ a b Mage DT, Donner EM (September 2004). "The fifty percent male excess of infant respiratory mortality". Acta Paediatr. 93 (9): 1210–5.  
  31. ^ Weber MA, Klein NJ, Hartley JC, Lock PE, Malone M, Sebire NJ (May 31, 2008). "Infection and sudden unexpected death in infancy: a systematic retrospective case review.". Lancet 371 (9627): 1848–53.  
  32. ^ Vennemann MM, Butterfass-Bahloul T, Jorch G, Brinkmann B, Findeisen M, Sauerland C, Bajanowski T, Mitchell EA (January 2007). "Sudden infant death syndrome: no increased risk after immunisation". Vaccine 25 (2): 336–40.  
  33. ^ Sudden Infant Death Syndrome (SIDS) and Vaccines
  34. ^ See FSID Press release.
  35. ^ Mage DT, Donner EM (2004). "Is SIDS at Borkmann's Point?". Medical Hypotheses and Research 1 (2/3): 131–7. 
  36. ^ Yang Z, Lantz PE, Ibdah JA (December 2007). "Post-mortem analysis for two prevalent beta-oxidation mutations in sudden infant death". Pediatr Int 49 (6): 883–7.  
  37. ^ Nevas M, Lindström M, Virtanen A, Hielm S, Kuusi M, Arnon SS, Vuori E, Korkeala H (January 2005). "Infant botulism acquired from household dust presenting as sudden infant death syndrome". J. Clin. Microbiol. 43 (1): 511–3.  
  38. ^ Millat G, Kugener B, Chevalier P, Chahine M, Huang H, Malicier D, Rodriguez-Lafrasse C, Rousson R (May 2009). "Contribution of long-QT syndrome genetic variants in sudden infant death syndrome". Pediatr Cardiol 30 (4): 502–9.  
  39. ^ Stray-Pedersen A, Vege A, Rognum TO (October 2008). antigen in stool is associated with SIDS and sudden infant deaths due to infectious disease"Helicobacter pylori". Pediatr. Res. 64 (4): 405–10.  
  40. ^ Bajanowski T, Vennemann M, Bohnert M, Rauch E, Brinkmann B, Mitchell EA (July 2005). "Unnatural causes of sudden unexpected deaths initially thought to be sudden infant death syndrome". Int. J. Legal Med. 119 (4): 213–6.  
  41. ^ Du Chesne A, Bajanowski T, Brinkmann B (1997). "[Homicides without clues in children]". Arch Kriminol (in German) 199 (1–2): 21–6.  
  42. ^ Williams FL, Lang GA, Mage DT (2001). "Sudden unexpected infant deaths in Dundee, 1882-1891: overlying or SIDS?". Scottish medical journal 46 (2): 43–47.  
  43. ^
  44. ^ Hymel KP (July 2006). "Distinguishing sudden infant death syndrome from child abuse fatalities.". Pediatrics 118 (1): 421–7.  
  45. ^ "About Statistics and the Law" (Website). Royal Statistical Society. (2001-10-23) Retrieved on 2007-09-22
  46. ^ Mitchell EA (November 2009). "SIDS: past, present and future.". Acta paediatrica (Oslo, Norway : 1992) 98 (11): 1712–9.  
  47. ^ Mitchell EA, Hutchison L, Stewart AW (July 2007). "The continuing decline in SIDS mortality". Arch Dis Child. 92 (7): 625–6.  
  48. ^ Jaafar SH, Jahanfar S, Angolkar M, Ho JJ (Jul 11, 2012). "Effect of restricted pacifier use in breastfeeding term infants for increasing duration of breastfeeding.". The Cochrane database of systematic reviews 7: CD007202.  
  49. ^ "What Can Be Done?". American SIDS Institute. 
  50. ^ L'Hoir MP, Engelberts AC, van Well GT, McClelland S, Westers P, Dandachli T, Mellenbergh GJ, Wolters WH, Huber J (1998). "Risk and preventive factors for cot death in The Netherlands, a low-incidence country". Eur. J. Pediatr. 157 (8): 681–8.  
  51. ^ "The Changing Concept of Sudden Infant Death Syndrome: Diagnostic Coding Shifts, Controversies Regarding the Sleeping Environment, and New Variables to Consider in Reducing Risk".  
  52. ^ Adams SM, Good MW, Defranco GM (2009). "Sudden infant death syndrome". Am Fam Physician 79 (10): 870–4.  
  53. ^ Koopmans L, Wilson T, Cacciatore J et al. (Jun 13, 2013). "Support for mothers, fathers and families after perinatal death". Cochrane Database of Systematic Reviews 6.  
  54. ^ Lozano R, Naghavi M, Foreman K, Lim S, Shibuya K, Aboyans V, Abraham J, Adair T, Aggarwal R, Ahn SY, et al. (Dec 15, 2012). "Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010.". Lancet 380 (9859): 2095–128.  
  55. ^ Sharma BR (March 2007). "Sudden infant death syndrome: a subject of medicolegal research.". The American journal of forensic medicine and pathology 28 (1): 69–72.  
  56. ^ a b c Bowman L, Hargrove T. Exposing Sudden Infant Death In America. Scripps Howard News Service.
  57. ^ Brathwaite-Fisher, T, Bronheim, S. Cultural Competence and Sudden Infant Death Syndrome and Other Infant Death: A Review of the Literature from 1990-2000. National Center for Cultural Competence, Georgetown University Center for Child and Human Development 2001. DOI:

Further reading

  • Ottaviani, G. (2014). Crib death - Sudden infant Death Syndrome (SIDS). Sudden infant and perinatal unexplained death: the pathologist's viewpoint. Berlin Heidelberg, Germany: Springer.  
  • Lewak N. "Book Review: SIDS". Arch Pediatr Adolesc Med 158 (4): 405.  

External links

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