What should I know about SIDS?

SIDS, or sudden infant death syndrome, is one cause of sudden unexpected infant death, and together they are the most common cause of death among babies between the ages of one month and one year. The exact cause of SIDS is not known, but one idea is that it is caused by a defect in the brain. It is also more common when a baby is infant formula-fed, placed to sleep on its tummy, or sleeps on a soft surface. Breastfeeding significantly reduces the risk of SIDS.

A) Describing SIDS

Sudden infant death syndrome (SIDS) is one cause of sudden unexpected infant death (SUID). Babies are at the biggest risk of SIDS between the ages of two months and four months.

While, in the past, rates for SIDS were as high as 2-6 deaths per 1,000 live births, more recent rates are reported to be 0.2-0.5 deaths per 1,000 live births in most countries (Goldstein 2016).

The exact cause of SIDS is unknown. One thought is that SIDS is caused by a defect in the baby’s brain that leaves the baby unable to react to low levels of oxygen or high levels of carbon dioxide in the blood (Bright 2018; Kinney 2019). Other suggested causes of SIDS include having a certain genetic makeup, abnormal heart rhythms, or an infection.

For more information, please contact your health-care providers.

B) Risk factors for SIDS

The risk of a baby dying of SIDS is increased by (Carlin 2017):

  • Not breastfeeding.
  • Allowing the baby to sleep on the stomach or side.
  • Dangerous bed-sharing.
  • Using soft bedding including blankets, pillows, bumper pads, and positioners.
  • Swaddling.
  • Being placed on a soft surface such as a sofa or couch.
  • Being placed where the baby’s head and neck is not supported such as a car seat or baby carrier.
  • Having a mother who smokes during pregnancy and after birth.
  • Being born premature or low weight.
  • Having a sibling or cousin who has died of SIDS.
  • Other unsafe practices.

C) Preventing SIDS

Breastfeeding significantly reduces the risk of SIDS. Immunizations have been reported to be protective of SIDS.

While pacifiers have been reported to decrease the risk of SIDS, the evidence is not enough to recommend pacifier use as a way of preventing it.


Bright FM, Vink R, Byard RW. The potential role of substance P in brainstem homeostatic control in the pathogenesis of sudden infant death syndrome (SIDS). Neuropeptides. 2018 Aug;70:1-8
Carlin RF, Moon RY. Risk Factors, Protective Factors, and Current Recommendations to Reduce Sudden Infant Death Syndrome: A Review. JAMA Pediatr. 2017 Feb 1;171(2):175-180
Goldstein RD, Trachtenberg FL, Sens MA, et al. Overall postneonatal mortality and rates of SIDS. Pediatrics. 2016;137(1):1-10
Kinney HC, Haynes RL. The Serotonin Brainstem Hypothesis for the Sudden Infant Death Syndrome. J Neuropathol Exp Neurol. 2019 Aug 9