New Report Explains Ongoing Prevalence of Sudden Unexpected Infant Death, or SUID

Safe Sleeping Baby Crib

Key Takeaways

  • Sudden Unexpected Infant Death rates have not changed significantly in the past 20 years. 
  • Research has shown that the majority of cases are preventable.
  • A safe sleep environment is the number one way to reduce these rates. 

Sudden Unexpected Infant Death (SUID) is an overarching term to define the sudden and unexpected death of an infant under the age of 1-year old.

A recent study published in Pediatrics, the official Journal of the American Academy of Pediatrics, has revealed that the majority of SUID cases are occurring due to unsafe sleep spaces for babies and thus, can be prevented with the correct education and support.

Support is Available

The loss of a baby is a traumatic event that requires love and support, not judgment. Resources and support are available to help parents, caregivers, and families who have experienced such loss. If you or someone you love needs further support, please reach out to any of the below organizations. 

  • First Candle offers support to families who have experienced the loss of a baby from SUID or SIDS. 
  • Hopeful Beginnings offers free Grief and Loss Counseling for both biological and adoptive families. 
  • NILMDTS offers bereaved families ways to honor the memory of their baby and connects families through their annual remembrance walk. 

SUID and SIDS Trends

SUID and SIDS (Sudden Infant Death Syndrome) are often confused because the terms have been redefined throughout the years.

Currently, SUID includes all causes of unexpected infant death during sleep, including SIDS, Accidental Suffocation or Strangulation in Bed (ASSB), illness, and trauma. SIDS is when death occurs suddenly in a seemingly healthy infant and no identifiable cause can be found even after a thorough investigation. 

Both SUID and SIDS did greatly reduce from the early 1990s when public health campaigns taught parents the importance of sleeping babies on their backs. However, data from the CDC shows that over the past twenty years, SIDS rates have decreased, but the rates of Unexplained Causes and ASSB increased. Overall this means that SUID rates remain relatively consistent.

Study Co-author and SIDS expert Fern R. Hauck, MD explains that these changing numbers are likely due to a reclassification of terms. 

“There has been a trend for the causes of death to move away from SIDS to these other categories, based on risk factors in the sleep environment, such as bedsharing, soft bedding, sleeping prone.” Explains Hauck, “This is known as diagnostic shift. So even though these factors would have been present 20+ years ago for many of the infant deaths called SIDS, now there is a reluctance to call these deaths SIDS.”

What Are the Real Rates of SUID? 

The study reviewed SUID cases across six states of the US and analyzed the circumstances surrounding these unfortunate events. It revealed that approximately 72% of cases occurred due to unsafe sleep environments. Only 1% had genuinely unknown causes of death with babies sleeping in safe environments (SIDS).

Dr Fern R. Hauck, MD, MS

Parents are not following all the guidelines and thus we are still seeing many infant deaths that are preventable

— Dr Fern R. Hauck, MD, MS

Authors of this study are concerned that results indicate some parents are not following the recommended sleep guidelines. "Parents are not following all the guidelines and thus we are still seeing many infant deaths that are preventable." Says Hauck. "It is important that we develop ways to work with parents on identifying the best ways to provide the most effective education."

Research is underway to determine at-risk populations to better provide support to these families. However, from this most recent study, researchers wish to highlight the most common causes of SUID in the hope of reducing prevalence.

Common Causes of SUID

Although many cases in the study remain unexplained, 31% of cases were confirmed or suspected ASSB. Hauck reveals the most common causes of ASSB included soft bedding, overlay, and wedging (also known as entrapment). “Soft bedding, overlay, and wedging are the most common mechanisms causing airway obstruction and death and therefore should be avoided.”

Soft Bedding

Babies should sleep on a firm mattress or surface. Soft mattresses, blankets, pillows, and soft toys all have the potential to cover a baby’s face. Although you may put your baby to sleep on their back, as they get older and wriggle around in bed, they can find themselves with their face in any of these items.

When your baby begins to roll over, they may be able to go from back to front, but not get off their tummy. Pillows and soft mattresses may block the flow of air in this circumstance. 

Sharing an adult bed, sleeping on a couch, or placing your baby on their side or stomach to sleep also increase their risk of suffocation. 


Overlay occurs when another person has accidentally covered the baby’s airway with their own body. This is why bed-sharing is not recommended. 

If you do have to take your baby into bed with you for feeding or comfort, ensure you stay awake. If you feel tired, ask another adult to stay awake and watch you both. Never have other children in the bed if you are taking your baby into bed with you for any reason. 

You should also never take your baby into bed with you if you are a smoker, have been drinking alcohol, or have taken any medication or drugs that will make it harder for you to wake up. 


Wedging is when a baby gets stuck between two surfaces, such as between the mattress and the sides of the crib, or between two couch cushions. 

It is essential that you have a firm mattress that fits securely in the crib. Do not sleep babies on couches. Also, do not leave babies unattended on beds not designed for babies. They risk falling off, even if you don’t think they can get to the edge. 

By avoiding soft bedding, and removing the opportunity for overlay or wedging, Hauck says, “That is the best way to reduce and hopefully fully eliminate these deaths.”

How to Prevent SUID

In the aforementioned study, the majority of SUID cases were found to be preventable. The best way to prevent SUID is to become familiar with safe sleeping practices and abide by them. 

Marion Koso-Thomas, MD

Every parent and caregiver can do something to help babies sleep safely.

— Marion Koso-Thomas, MD

Safe to Sleep® is a national campaign aimed at teaching parents and professionals about safe infant sleeping. Scientific advisor for Safe to Sleep, Dr Marion Koso-Thomas says “Every parent and caregiver can do something to help babies sleep safely.” She offers the following tips

Sleep Baby on Their Back

Koso-Thomas advises parents that sleeping a baby on their back for sleep is one of the most important steps in keeping your baby safe. “Using the back sleep position for every sleep, even naps, is a key step—the back sleep position carries the lowest risk for Sudden Infant Death Syndrome (SIDS)” She says. 

Use a Firm, Flat Surface

Even if your baby falls asleep in their car seat or pram, moving them to a firm, flat surface as soon as you can is safest. Koso-Thomas says, “The latest research findings also highlight the importance of a firm, flat sleep surface that is free of soft and loose bedding, stuffed toys, and crib bumpers for preventing deaths related to the sleep area.”

Avoid Soft Bedding, Loose Items, and Toys

Soft bedding is one of the main causes of ASSB and so should be avoided. “Keeping soft, loose, and other items out of the sleep area and always using the back sleep position reduces the risk for SIDS, as well as for accidental suffocation, strangulation, and entrapment.” Reminds Koso-Thomas. 

“Remember that babies, especially newborns, can’t move their bodies to breathe more easily.” She continues, “So if their face gets covered by a blanket, becomes pressed against a crib bumper, or sinks into a soft blanket or mattress..., they can’t change their position to get more oxygen.” 

Keep Baby's Arms Free

If you are swaddling your baby, it is also important to stop swaddling once your baby starts to show signs of rolling. This way, if they first roll over in their sleep space, their arms are free to help them prop themselves up if needed. 

Be Aware of Your Baby's Temperature

To keep your baby warm without loose blankets in the crib, using a wearable blanket or footed pajama suit is safest. You can layer clothing on your baby to keep them warm.

Hauck advises, “Keep in mind that babies should not be excessively bundled (overheating is a risk factor for SIDS). A rule of thumb is to add one layer more than the parent is comfortable wearing. For example, if Mom is wearing two layers, baby needs three.”

She also suggests, that if you feel your baby does need additional warmth, English and Australian guidelines both recommend placing your baby's feet at the end of the cot. From here, tuck a light blanket firmly in at the feet and sides. Only allow it to reach as high as your baby's armpits. This way your baby is less likely to wriggle their face under the blanket.

What This Means For You

Every opportunity should be taken by healthcare professionals to teach parents how to sleep their baby safely. If your health care provider doesn’t start the conversation, you are encouraged to do so. Ask questions and find your answers.

If you feel you are unable to afford the correct safe sleeping environment for your baby, your health care team can connect you with services that offer free or low-cost safe sleeping items. Alternatively, you can request access to a free crib through Cribs for Kids. Setting up a safe environment for your baby is essential to prevent unexpected and often preventable accidents from occurring. 

5 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Parks SE, Erck Lambert AB, Hauck FR, Cottengim CR, Faulkner M, Shapiro-Mendoza CK. Explaining Sudden Unexpected Infant Deaths, 2011–2017. Pediatrics. 2021;147(5):e2020035873. doi:10.1542/peds.2020-035873

  2. National Institutes of Health. Common SIDS and SUID Terms And Definitions | Safe to Sleep.

  3. Centers for Disease Control and Prevention. Data and Statistics for SIDS and SUID |CDC.

  4. American Academy of Pediatrics. How to Keep Your Sleeping Baby Safe: AAP Policy Explained -

  5. American Academy of Pediatrics. How to Keep Your Sleeping Baby Safe: AAP Policy Explained -