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Medical Author:

Patrick L. Carolan, MD

Medical Editor:

David Perlstein, MD, MBA, FAAP

David Perlstein, MD, MBA, FAAP

Dr. Perlstein received his Medical Degree from the University of Cincinnati and then completed his internship and residency in pediatrics at The New York Hospital, Cornell medical Center in New York City. After serving an additional year as Chief Pediatric Resident, he worked as a private practitioner and then was appointed Director of Ambulatory Pediatrics at St. Barnabas Hospital in the Bronx.

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In this Article

• What is sudden infant death syndrome (SIDS)?
• What is the cause of SIDS?
• What are the risk factors for SIDS?
• How is SIDS diagnosed?
• Can SIDS be prevented?
• Does the supine (back) sleep position cause any problems for infants?
• What support is available to parents who are coping with an infant loss due to SIDS?
• Where can people get more information about sudden infant death syndrome (SIDS)?
• Sudden Infant Death Syndrome (SIDS) At A Glance
• SIDS Index

Research studies continue to demonstrate a greater risk for SIDS among male infants. SIDS is observed more frequently during winter months than summer months, although this distribution is not as pronounced in recent years as it had been in the past. In the United States, both African American and Native American infants have a higher rate of SIDS than do Caucasian, Hispanic, and Asian infants.

Certain infant-care practices have an effect on the risk for SIDS. Most notable is the increased risk associated with the placement of infants on their stomach (prone sleep position) for sleep. The "Back to Sleep" campaign was launched in the United States in 1994 and embodies a public-health effort encouraging families to place infants on their backs (supine sleep position) to sleep. Since the start of this campaign, SIDS rates have dropped 50% in the United States. Similar drops have been observed worldwide, highlighting the importance of the supine sleep position for infants.

Other factors increasing the risk for SIDS include exposure to cigarette smoke, bed-sharing or co-sleeping, over-bundling or the covering of the infant's head by bed covers, loose bedding, or blankets. Recent research studies suggest that breastfeeding and pacifier use may reduce the risk of SIDS.

Sudden infant death remains an unpredictable, unpreventable, and largely inexplicable tragedy. The baby is seemingly healthy without any sign of distress or significant illness prior to the incident.

• Death occurs rapidly while the infant is sleeping.



• Typically, it is a silent event. The baby does not cry.



• The infant usually appears to be well developed, well nourished, and is generally felt to be in good health prior to death. Minor upper respiratory or gastrointestinal symptoms due to viruses like respiratory syncytial virus (RSV) are not uncommon in the last two weeks preceding SIDS.

Sudden, unexpected infant death (SUID) is a general term used for the circumstance of an infant death which occurs suddenly and in an unexpected manner. SIDS is a diagnosis of exclusion, meaning that other causes of death must be ruled out. The cause of an infant's death can be determined only through a process of collecting information and conducting, at times, complex forensic tests and procedures. All other recognizable causes of death are investigated prior to making the diagnosis of SIDS.

Four major avenues of investigation aid in the determination of a SIDS death: postmortem lab tests, autopsy, death-scene investigation, and the review of victim and family case history.

• Postmortem laboratory tests are done to rule out other causes of death (for example, electrolytes are checked to rule out dehydration and electrolyte imbalance; bacterial and viral cultures are obtained to evaluate whether an infection was present). In SIDS, these laboratory tests are generally not revealing.



• An autopsy provides clues as to the cause of death. In 15%-25% of sudden, unexpected infant deaths specific abnormalities of the brain or central nervous system, the heart or lungs, or infection may be identified as the cause of death. The autopsy findings in SIDS victims are typically subtle and yield only supportive, rather than conclusive, findings to explain SIDS.



• A thorough investigation of the death scene consists of interviewing the parents, other caregivers, and family members, collecting items from the death scene, and evaluating that information. A detailed scene investigation may reveal a recognizable and possibly preventable cause of death.



• A parent or caregiver may be asked these questions:



• Where was the baby discovered?



• What position was the baby in?



• When was the baby last checked? Last fed?



• How was the baby sleeping?



• Where there any recent signs of illness?



• Was the infant taking any medication, either prescription or over-the-counter?



• You should let your doctor know about any family or infant medical history. Family history to note would include any previous history of unexplained infant death, sudden cardiac death, and metabolic or genetic disorders, for example.