What are the causes of Sudden Infant Death Syndrome (SIDS)?

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Last updated: February 24, 2025View editorial policy

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From the Guidelines

The exact cause of Sudden Infant Death Syndrome (SIDS) remains unknown, but it's believed to result from a combination of factors, including underlying vulnerabilities and external stressors during a critical period of development, with risk factors such as exposure to tobacco smoke, overheating, and soft bedding playing a significant role. The leading theory suggests that SIDS occurs when a baby with an underlying vulnerability, which may involve abnormalities in the brain's arousal system, faces external stressors during a critical period of development 1.

Key Risk Factors

  • Exposure to tobacco smoke during pregnancy and after birth is a major risk factor for SIDS, as stated in the 2016 recommendations for a safe infant sleeping environment 1
  • Overheating, soft bedding, and sleeping on the stomach or side are also significant risk factors 1
  • Maternal alcohol use and illicit drug use have been associated with an increased risk of SIDS, independent of prenatal cigarette smoking exposure 1

Recommendations for Reduction of SIDS Risk

  • Babies should sleep on their backs on a firm surface, in a smoke-free environment, and without loose bedding or soft objects in the crib to reduce the risk of SIDS 1
  • Breastfeeding and room-sharing (but not bed-sharing) with parents have also been associated with a lower risk of SIDS 1
  • Routine immunization has been found to have a protective effect against SIDS, with a meta-analysis showing a multivariate summary OR for immunizations and SIDS to be 0.54 (95% CI: 0.39–0.76) 1

Importance of a Safe Sleep Environment

  • A safe sleep environment can reduce the risk of all sleep-related infant deaths, including SIDS, and is a critical component of SIDS prevention 1
  • The American Academy of Pediatrics recommends a safe sleep environment that includes supine positioning, use of a firm sleep surface, room-sharing without bed-sharing, and avoidance of soft bedding and overheating 1

From the Research

Causes of Sudden Infant Death Syndrome (SIDS)

The exact cause of SIDS is still not fully understood, but several factors have been consistently associated with an elevated risk. These include:

  • Maternal smoking or exposure to substances of abuse during pregnancy 2, 3
  • Overheating and overinsulation 2, 4
  • Artificial feeding 2
  • Prone sleeping position 2, 5, 3, 4
  • Soft bedding 5, 3
  • Parental use of tobacco or alcohol 6
  • Inclined surfaces and loose bedding 6

Modifiable Risk Factors

Several modifiable risk factors have been identified, including:

  • Sleeping position: supine sleep position is recommended 5, 3, 6
  • Sleep surfaces: safe sleep surfaces are recommended 6
  • Room sharing: room sharing is recommended 6
  • Breast milk feeding: breast milk feeding is recommended 6
  • Pacifier use: pacifier use is recommended 6
  • Avoiding overheating, loose bedding, and inclined surfaces 6

Non-Modifiable Risk Factors

Several non-modifiable risk factors have been identified, including:

  • Premature birth 5
  • Perinatal risk factors 5
  • Genetic risk factors 3, 4
  • Neuropathological factors, such as hypoplasia or defective transmitter function in the medullary arcuate nucleus 4
  • Infantile epilepsies or status epilepticus, and genetic metabolic encephalopathies 4

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Sudden infant death syndrome.

CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 2006

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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