Frequently asked questions

The Minnesota Sudden Infant Death (SID) Center at Children’s has prepared the following frequently asked questions to help you better understand SIDS and SUID.

What is sudden infant death syndrome (SIDS)?

Sudden infant death syndrome (SIDS) is the sudden, unexpected death of an apparently healthy infant usually under one year of age that remains unexplained after a complete case investigation that includes a scene investigation, autopsy and review of the medical history (NICHD 1989). SIDS is a type of SUID (see below).

What is sudden unexpected infant death (SUID)?

SUID (pronounced SUE-IDD ) is a term used to describe any sudden and unexpected infant death, explained or unexplained, that occurs during infancy. SUIDs can be attributed to SIDS, accidental suffocation, asphyxia, entrapment, infection, ingestions, metabolic diseases, trauma (intentional or unintentional), etc. In some cases where the findings are not clear or not enough information is available, the death may be attributed to undetermined causes (CDC 2012).

Many SUIDs are sleep-related and are due to baby sleeping in an unsafe sleep environment such as tummy sleep position, sleeping on a sofa or adult bed (alone or with others), the presence of pillows, blankets, fluffy bedding, etc.

These deaths are often determined to be accidents or unintentional injury caused by suffocation, entrapment (when baby gets trapped between two objects, such as a mattress and wall and can’t breathe); or strangulation (when something presses on or wraps around baby’s neck, blocking baby’s airway). These deaths are not SIDS.

How many SIDS and SUIDs occur each year?

There are about 3,400 sudden, unexpected infant deaths in the United States each year. Of these, approximately half are attributed to SIDS (National Vital Statistics report 2015).

Since the beginning of the Back to Sleep campaign in 1994, the SIDS rate in the United States has dropped by more than 50%.

Although the overall SIDS rates have declined in all populations throughout the United States, disparities in SIDS rates remain, with African Americans and American Indian babies experiencing a rate 2 to 3 times that of Caucasian babies (National Vital Statistics report 2012).

How is a cause of death determined?

All sudden and unexpected deaths — whether it be an adult or child — become the jurisdiction of the local medical examiner or coroner, the medical-legal system.

Medical and legal experts rely on these three key components to determine a cause of death:

  1. Thorough death scene investigation
  2. Autopsy
  3. Review of infant’s and family’s medical records and histories.

Often, the cause of an infant death can be determined only through a process of collecting information, conducting sometimes complex forensic tests and by talking with parents, other caregivers and physicians.

In the past, medical examiners attributed most sleep related deaths to SIDS. Now they will often describe infant deaths using a greater variety of terms, such as “sleep related infant deaths,” “accidental suffocation,” or “sudden unexplained infant death” (Network of Infant Toddler Research, 2013).

When a death is sudden and unexplained, investigators, including medical examiners and coroners, call on forensic experts who apply their expertise in medicine and the law to help determine a cause of death.

In most cases, the death investigation is led by the medical examiner or coroner for the county in which the death occurred. The medical examiner or law enforcement officers conduct a thorough death scene investigation. The medical examiner/coroner uses information from the death scene and case histories along with all autopsy results to make the final cause of death determination.

What do current research findings and theories indicate?

Research has suggested that SIDS occurs when systems inside the infant’s body cannot overcome challenges in the environment or outside stressors. Scientists have found physiological differences in the bodies of SIDS infants, in the areas of brain development and parts of the nervous system that control breathing and heart rate. Substances, such as serotonin, in the brains of SIDS infants that carry messages between cells may also be less developed and present in lower quantities than in other babies.

It is likely that there are many explanations for why babies die suddenly and unexpectedly, as well as more than one means of prevention. Significant progress has been made to identify factors that put a baby at risk. Tummy sleeping, unsafe sleep practices like bed sharing, smoke exposure and overheating are risk factors that caregivers can change. There is a growing body of evidence that unsafe sleep practices are a leading risk factor for SIDS as well as sleep related infant deaths such as accidental suffocation.

Learn more about current SIDS research findings.


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