Understanding Sudden Infant Death Syndrome (SIDS): Highlights of its Epidemiology and History

A sad story

What is SIDS?

• SIDS is sudden, explainable death, usually during sleep, of a seemingly health baby less than a year old
• Also known as cot/crib death because the infants often die in their cots/cribs
• Diagnosis of exclusion
• Knowledge of epidemiology of SIDS was non-existent before the 1960’s.
• In 1969 the definition was created by Dr J Bruce Beckwith

Importance of SIDS issue

What causes SIDS?

A combination of physical and sleep environmental factors can make an infant more vulnerable to SIDS.

• Physical factors:
  • Brain abnormalities
  • Low birth weight
  • Respiratory infection
• Sleep environmental factors:
  • Sleeping on the stomach or side, on a soft surface, with blanket, or with parents
• Too close from a heat source (overheating)

Why co-sleeping can be dangerous

What are the possible risk factors?

• Identified several factors that may increase a baby’s risk:
  • Sex: boys are more likely to die of SIDS
  • Age: most vulnerable during the second and third months
  • Race: American Indian or Alaska Native infants are more likely
  • Family history: having siblings or cousins die of SIDS are higher risk
  • Being premature
  • Secondhand smoke
  • Maternal risk factors
  • Breastfeeding: lower SIDS (however Honk-Kong is a counter-example)
• No clear mechanism and cause that has been identified

SIDS scenario in the USA by ethicity

Modifiable risk factors

Four modifiable and other major risk factors for cot death: the New Zealand study ( Mitchell et. al., 1992)

Risk factors : a triple-risk model

Trachtenberg et. al., 2012 found that the risk profile has changed since the back-to-sleep campaign, the prevalence of simultaneous risks has remained consistent

• Intrinsic and extrinsic risks provide unification into one underlying triple-risk model and insights into potential underlying mechanisms
• 90% of SIDS infants were subject to at least risk factors represent in triple-risk model
• 5% of the SIDS infants had no identifiable extrinsic risk factor

US Government’s initivatives and successes

• The Back to Sleep 1992 and Safe to Sleep 1994 campaigns
• Since the start of the campaign, SIDS rates in the United States have decreased by almost 50%, both overall and within various racial/ethnic groups.
• However, SIDS remains the leading cause of death for U.S. infants
• Some populations are also at high risk for SIDS.
• So the campaign collaborators and its partners still have work to do.
• Impressive decline of SIDS rate in San Diego County (from 65 to 25 cases/year) allowed by the full establishment of the principle

SIDS data for 15 countries

• Highest SIDS rates (0.5/1000 live births) are in New Zealand and the United States and lowest rates (<0.2/1000) are in Japan and the Netherlands

SIDS scenario in the USA over time

• Large decrease in SIDS rates from 1990

Some evidence of reduced SIDS

Reduced IMR by reducing SIDS

SIDS was the leading cause of death in children between one month and one year of age in 2013.

Epidemiological studies with SIDS

Tips to reduce your baby’s risk

• Spreading the words to parents, but also caregiver such as grand-parents or brothers and sister
• One out of five SIDS deaths occurs when a baby is in day care or being watched by someone other than a parent, according to research in the journal Pediatrics.

Tips to reduce your baby’s risk

Source: Children’s National Health System