Sudden Infant Death Syndrome (SIDS)

Dr. Tafadzwa Kasambira, M.D., M.P.H. is a pediatrician who received his undergraduate training at McGill University in Canada, and graduated in 2002 from Tufts University School of Medicine, where he also completed a degree in public health. He completed his pediatric residency training at Harvard University in 2005,  and completed a fellowship in infectious diseases at Johns Hopkins University in 2008. He has been a medical officer at the FDA for the last six years. He and his husband are the proud fathers of three children.

Most parents are not unfamiliar with the act of creeping into their infants' room at night to check to see if they are still breathing. Few ever find out that they are not. The phenomenon known as Sudden Infant Death Syndrome (SIDS) is an ominous and devastating one, and is, by definition, unexplained, making the loss experienced that much more difficult to accept.

Our family has not gone through the pain of losing a child from SIDS, but I can recall clearly our mild paranoia over ensuring that this phenomenon never happened to any of our three children. One can become slightly neurotic after becoming a first-time parent, and this extreme concern extends to the realm of their sleep, often resulting in the lack of the same for us, the parents. We would check on our eldest daughter, Wordgirl, constantly when she was an infant, turning up the baby intercom to maximum reception so that we could hear from anywhere in the house if her rhythmic breathing ever stopped suddenly.

SIDS is the leading cause of death in the United States for infants aged one month to one year, and more than 2,000 die from this phenomenon annually. The exact cause of SIDS is unknown, but is thought by some to be due to the fact that infants sleeping on their front (prone position) may not be able to acquire enough oxygen when their faces are against the sleeping surface, nor are the youngest ones able to lift their heads or reposition their bodies when in an asphyxiating environment.

A major reduction in the incidence of SIDS was seen following the 1992 recommendation by the American Academy of Pediatric (AAP) that infants be placed to sleep on their back (supine position) or side (lateral position). In 1994, the National Institute of Child Health and Development (NICHD) launched the “Back To Sleep” campaign to help disseminate information about this recommendation. The message was further refined in 1996, after research showed that there still existed a risk of SIDS when infants were placed to sleep on their sides, as they could roll onto their fronts inadvertently. As a result, the recommendation became that infants only be placed to sleep on their backs, and not on their fronts or on their sides.

SIDS is usually deemed to be the cause of an infant fatality when the death cannot be explained after a thorough case investigation (1). Sudden unexpected infant death (SUID) is a larger group of conditions that includes SIDS, and the fatalities may be explained or unexplained. SUID may occur secondary to asphyxia, entrapment, suffocation, infection, ingestions, metabolic diseases or trauma (accidental or non-accidental).

The risk of death in infants who are placed to sleep on their front is as much as 19 times that of infants who are placed on their back to sleep. The incidence of SIDS has plateaued in recent years, while there has been an increase in other causes of sleep-related infant deaths, such as those outlined above for SUID. The most recent recommendations by the AAP explore these other causes in more detail, highlighting the importance of the sleep environment in the etiology of these infant deaths (1).

A friend and colleague recently published a paper that explored the risks of the sleep environment at different times during infancy, specifically, in younger (0 to 3 months) and older (4 months to 364 days) infants (2). He and his research team found that deaths in younger infants were more likely to be associated with sharing a bed or sleeping in an adult bed or on a person (i.e., with the risk of the adult rolling on top of the infant), while older infants were more likely to die when they rolled onto an object in the sleep area, such as a blanket or stuffed animal, and also when they changed their sleep position from the back to the front or side position.  When infant deaths occur in a bed-sharing situation, the etiology is often unclear, because it is difficult to determine whether the death occurred due to SIDS or secondary to accidental suffocation. Of note, sofas, in particular, have been found to be a particularly dangerous place for infants, and deaths on this sleep surface account for almost 13% of all sleep-related infant deaths (3).

Current recommendations designed to prevent SIDS and other causes of sleep-related infant death, include the following: as discussed previously, “back-to-sleep” (placement of the infant in the supine position); use of a firm sleeping surface; avoidance of soft bedding, overheating, and exposure to tobacco smoke; if room-sharing, no bed-sharing; consideration of a pacifier for use by the infant during sleep; and routine immunization, one reason being that pertussis, for which the DTaP vaccine is administered to infants, may cause hypoxia (deprivation of oxygen supply) or even apnea (cessation of breathing) in some young infants.

If infants who are placed on their backs to sleep do roll onto their front, the AAP states that the infants do not need to be repositioned onto their backs; that said, it is prudent for caregivers to keep the sleep environment free of objects that might impede the infant’s breathing, should they roll over. Some parents worry that the infant may be cold without the use of a blanket; it is advisable instead to use a body sleeper, in which the infant’s head and neck will not become entangled.

The vast majority of infants will emerge from the period of infancy healthy and without major difficulties, and most families will never be touched by the devastation wrought by the death of their baby due to SIDS. Taking simple preventive measures, such as parents and caregivers placing the infants on their backs during sleep and paying close attention to the infants' sleeping environment, can reduce significantly the risk of SIDS and sleep-related infant death.

Legal Disclaimer: This article is designed to provide general information related to pediatric care. The information presented in this article should not be construed as formal medical advice, nor is it intended to create a doctor-patient relationship. The content is intended solely for informational and not for treatment purposes.

This article is not a substitution for professional medical diagnosis or treatment.



1. Task Force on Sudden Infant Death Syndrome and Moon RY. SIDS and Other Sleep-Related Infant Deaths: Expansion of Recommendations for a Safe Infant Sleeping Environment.Pediatrics2011;128(5):1030-9

2. Colvin JD, Collie-Akers V, Schunn C and Moon RY. Sleep Environment Risks for Younger and Older Infants. Pediatrics2014;134(2);e406-12

3. Rechtman LR, Colvin JD, Blair PS, and Moon RY. Sofas and infant mortality. Pediatrics 2014;134(5):e1293-300



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Posted by Dr. T. Kasambira

Dr. Kasambira is a pediatric infectious diseases physician and science writer who has worked for years in clinical study management and drug regulation. He is married, has three children, and lives in the Washington, D.C. area.

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