SIDS Risk Factors and Protective Factors

Lifespan Health
Public Health

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What you need to know

​Risk Factors

While Sudden Infant Death can strike any infant, researches have noted several factors that may increase a baby's risk.

  • Certain risk factors have been identified during the pregnancy. To prevent possible risk factors, maintain a healthy pregnancy by getting early and consistent prenatal care, staying within the overall weight gain goals, and stop smoking, drinking alcohol or using “street" drugs.
  • Several factors increase a baby's risk of Sudden Infant Death. Some risk factors may be reduced by maintaining a healthy pregnancy, a smoke free home and providing a safe sleep environment.
  • Certain environmental aspects and baby positioning also provide risks for Sudden Infant Death.
  • The Triple-Risk Model describes three conditions, that when combined, may lead to a death from SIDS.

1. Pregnancy risk factors

Research indicates that some infants are at a higher risk of SIDS because of certain risk factors identified during the pregnancy:

  • Mothers who have inadequate prenatal care
  • Abnormal placenta
  • Low weight gain during pregnancy
  • Maternal age under 20 years old
  • Anemia
  • History of infections like sexually transmitted diseases or a urinary tract infection
  • History of drug use, smoking or alcohol use during or after pregnancy

2. Babies at Risk

Several factors increase a baby's risk of Sudden Infant Death Syndrome.

  • Low birth weight infants
  • Premature infants
  • Sex of the baby-boys have a higher incidence of SIDS
  • Race: African American, American Indian or Native Alaskan babies have a higher risk for SIDS
  • Babies who sleep on their stomachs
  • Babies used to sleeping on their back are switched to sleep on their stomachs
  • Secondhand smoke
  • Baby's age Increased vulnerability to SIDS when they are 1 to 6 months old with the peak time during 2-3 months of age. SIDS may occur up to one year of age.
  • Overheating / over dressing your baby Increased risk of SIDS
  • Evidence of a recent respiratory infections within four weeks of death was commonly revealed on autopsies
  • Siblings of a baby who died of SIDS have a small risk of SIDS possibly linked to a genetic disorder. 

3. Sleep associated risks

2009 State of Nebraska Child Death Review Team Report:

Sudden Unexpected Infant Death by Race/Ethnicity Total %
Native American28.7%
Asian/Pacific Islander00.0%
Total (N)23100%
Hispanic Ethnicity28.7%


Sudden Unexpected Infant Death Total %
Total (N)23100%


Sleep-Associated Death

Risk Factors

Total %
Prenatal or postnatal smoke exposure1664%
Ageinappropriate sleep surface 1560%
Found on side or stomach1352%
Bedding–related issues1144%
Put to sleep on side or stomach936%
Current/recent respiratory infection936%
Prenatal drug exposure312%
No known risk factors 04%


Definitions for above risk factors

  • Prenatal or postnatal smoke exposure: 64% of infants had documented exposure to tobacco smoke either while mom was pregnant or after infant was born.
  • Age inappropriate sleep surface: 60% of infants were sleeping in or on something other than a safety-approved crib, playpen or baby bed.
  • Found on side or stomach: At time of death, 52% of infants were positioned on his/her side or stomach.
  • Bed sharing: At the time of death, close to half of infants, 48%, were sleeping with an adult or other child.
  • Bedding-related issues include: blankets and/or sheets found over the infant's head or around their mouth or nose, stuffed animals in the bed, or having been placed on a pillow etc. 44% of babies has bedding-related issues at the time of death.
  • Put to sleep on side or stomach: 64% of infants were reported to have been found on their backs.  36% of babies were found on side or stomach.
  • Current/recent respiratory infection: 36 % of infants were reported to have a current or recent (within the past 2 weeks) respiratory infection. Respiratory infection is a likely contributor to impaired breathing.
  • Prenatal drug exposure: 12 % of babies had prior drug exposure during pregnancy before they were born.

4. Triple Risk Model

Researchers use the Triple-Risk Model for examining Sudden Infant Death Syndrome (SIDS).  The Triple-Risk Model defines three conditions, that when combined, may lead to a death from SIDS.

Critical Development

During the baby's first 6 months of life, there is rapid change and development in the brain.  This growth may be evident like the sleep and awake patterns, or very subtle changes may be seen like changes in respiration, blood pressure or temperature.  The peak incidence of SIDS occurs between 1 – 4 months of age; 90% of cases occur before 6 months of age.  Babies continue to be at risk for SIDS up to 12 months.

Vulnerable Infant

Many of the babies that die of SIDS have had some form of upper respiratory infection in the prior 4 weeks.  Babies born early (premature) are at a higher risk.  Research shows that at the time of death, some SIDS babies have decreased levels of serotonin.  An underlying brain abnormality may also make the baby vulnerable.

Outside Stressors

Most babies can survive environmental stressors like second hand smoke, over-heating, and sleeping on their stomachs.  However, babies that are vulnerable may not be able to overcome these outside stressors.  “Although these stressors are not believed to single-handedly cause infant death, they may tip the balance against a vulnerable infant's chances of survival."(5)

Icon of triple factor  

All three conditions of the Triple Risk Model need to be present for SIDS to occur:

  1. Undetected vulnerability in the baby
  2. The baby is in a critical developmental period of growth
  3. Outside stressors are present

Risk reduction means removing as many challenges from the baby's environment as possible during their first year of life.  Position the baby on their back to sleep or remove second hand smoke.  Eliminating one or more of the outside stressors can reduce the risk of SIDS.


Protective Factors

Researchers have discovered some protective measures you can take to help protect your baby from SIDS. Breastfeeding and a safe sleep e​​nvironment can help.

Safe Sleep Environment

What does a safe sleep environment look like? On their back, in their own crib, every time. Print Safe Sleep Environment.


Breastfeeding studies have shown a decreased incidence of SIDS in breastfed babies. Breastfeeding is the normal way of providing babies with the nutrition needed for healthy growth and development. “Virtually all mothers can breastfeed, provided they have accurate information, and the support of their family, the health care system and society at large".(6) The World Health Organization recommends breastfeeding exclusively for the first 6 months of life, with continued breastfeeding along with doctor recommended baby food up to two years of age or beyond.  Breastfeeding reduces the risk of hospitalization with gastrointestinal and respiratory infections.

A meta-analysis of 23 studies published up to 1997 examining the relationship between SIDS and breastfeeding found the overall risk of SIDS twice as great for formula fed infants compared with breastfed infants. Infant sleep studies have shown that breastfed infants are more easily aroused than formula-fed infants, which may be a mechanism for the protective effect of breastfeeding against SIDS.(7)

Breast-feeding reduces the risk for sudden infant death syndrome (SIDS) by approximately 50% at all ages throughout infancy. Exclusive breast-feeding at age 1 month was associated with half the risk for SIDS. Both partial breast-feeding and exclusive breast-feeding were linked to a reduced risk for SIDS. Ever breastfeeding was associated with a reduced risk of SIDS.

The advice to breastfeed should be included as a prevention measure. Mothers need to be cautious about breastfeeding in bed or any situation where you may fall asleep while breastfeeding your baby. Always place the baby back in his or her crib or bassinet after breastfeeding.(8) On their back, in their own crib, every time.

Documents used in the development of this content:

  1. About Sudden Unexpected Infant Death and Sudden Infant Death Syndrome. Centers for Disease Control and Prevention. [Online] 07 07, 2014.  About SUID and SIDS
  2. Safe to Sleep. National Institute of Child Health and Human Development. [Online] 07 07, 2014. [Cited: 07 07, 2014.]  NICHD
  3. Sudden Infant Death Syndrome (SIDS). KidsHealth. [Online] [Cited: 07 07, 2014.]  Kids health
  4. SIDS Risk Factors and Causes of SIDS. SIDS America . [Online] [Cited: 07 07, 2014.]  SIDS America
  5. Research on Possible Causes of SIDS. Safe to Sleep Public Education Campaign. [Online] 09 23, 2013. [Cited: 07 09, 2014.]  NICHD
  6. Safe Sleeping Recommendations from the American Academy of Pediatrics
  7. Fern Hauck, MD, MS, et al. Breastfeeding and Reduced Risk of Sudden Infant Death Syndrome: A Meta-analysis. Pediatrics. July 1, 2011, 2011, Vol. 128, 1
  8. World Health Organization. Health Topics Breastfeeding. 07/10/1