Sudden Infant Death Syndrome and Sudden Unexpected Infant Death: What We Know

Few losses are as hard as the sudden death of a baby. If this has happened to you, grief after such a loss is often tangled up with guilt and “what if” questions, and you do not have to face it alone. There is help on this site and elsewhere. This article explains what the terms mean and what researchers know, in plain terms. It is not medical advice.

What is SUID, and what is SIDS?

SUID stands for sudden unexpected infant death. The CDC says it includes sudden infant death syndrome (SIDS), accidental suffocation and strangulation in bed, and deaths of unknown cause. In other words, SUID is the big category, and SIDS is one part of it. The MSD Manual describes SIDS as the sudden death of an infant that stays unexplained after an investigation, and says the exact cause is not known. Many deaths first labeled SUID are later found to have a cause, such as suffocation in an unsafe sleep space.

How common is it?

The CDC reports that SUID accounts for approximately 3,400 deaths among infants under one year in the United States each year. A rate is how many happen for every 100,000 babies born. The CDC says the SUID rate fell from 154.6 per 100,000 live births in 1990 to 93.9 in 1999 after clinical guidance and public health campaigns on safe infant sleep. But progress has stalled, and from 2020 to 2022 the rate rose from 92.9 to 100.9.

What is known about the causes?

Not everything. The MSD Manual says the cause of SIDS is unclear, though a number of risk factors have been identified, and that certain measures seem to reduce the risk. SIDS is rare, but it is one of the most common causes of death in babies under a year old. It also says that infants who live in poverty are at greater risk of SUID. The Children’s Safety Network used CDC data from 2016. It reported that about 42 percent of SUID deaths were SIDS, 34 percent had unknown causes, and 24 percent were accidental suffocation and strangulation in bed. It also noted that SUID rates among American Indian and Alaska Native infants and Black infants were more than twice those of white, Hispanic, and Asian and Pacific Islander infants.

What is safe sleep?

The guidance that has saved the most lives. The CDC says the American Academy of Pediatrics recommends that infants be placed to sleep on their backs on a flat, firm, nonshared sleep surface, without soft bedding. The MSD Manual describes the surface as a safety-approved crib mattress covered by a fitted sheet. It says deaths from SIDS fell dramatically as more parents began putting babies on their backs for every sleep. The national “Safe to Sleep” campaign, a partnership of the CDC and the National Institute of Child Health and Human Development, formerly called Back to Sleep, spreads these messages. Ask your baby’s doctor for current advice.

What happens after a baby dies suddenly?

An investigation to try to find out why, which often involves a medical examiner or coroner. The CDC says every SUID is classified to separate explained from unexplained deaths and to record whether unsafe sleep factors contributed. This can feel intrusive during grief. It may help to ask a trusted person to be with you for the questions. See Coroner vs. Medical Examiner for how it works.

Where can I find support?

For the grief itself, see Losing a Child, Coping With Sudden or Traumatic Loss, and, if the loss happened around birth, Stillbirth and Pregnancy Loss. If you are struggling, a grief counselor can help, and you can call or text 988 at any time to reach a crisis counselor.