Sudden, unexplained infant deaths are defined as deaths for which the cause of death is unknown. These deaths may be still under (or needing further) investigation or they may have completed a thorough investigation and determined the death to be SIDS. When first discovered, many infant deaths do not have an obvious cause. These sudden, unexplained (unexpected) infant deaths, which include suffocation, poisoning, falls, SIDS, and others (see list below), may not be easily distinguishable from one another. None is due to a chronic disease or illness and none is explainable without a more careful examination.

          For a medical examiner or coroner to determine the cause of the death, an investigator(s) needs to conduct a thorough investigation including examination of the death scene and a review of the infant's clinical history. A complete autopsy needs to be performed ideally using information the investigator has gathered. Even when a thorough investigation is conducted, it may be difficult to separate SIDS from other types of sudden, unexplained infant deaths. After the cause of death has been determined, infant deaths that were initially classified as sudden, unexplained infant death can be referred to as sudden, unexpected infant deaths since they are no longer unexplained deaths.

What are the causes of Sudden Unexplained Infant Death (SUID)?

Accidental suffocation or strangulation in bed

(e.g., the infant suffocates while trapped between an adult bed frame and the wall)

Other accidental suffocation or strangulation

(e.g., the infant suffocates by a plastic bag)

Accidental poisoning

(e.g., the infant eats some adult aspirin that were left on a coffee table)

Obstruction of respiratory tract

(e.g., the infant chokes on a coin, food, or other object)

Accidental falls

(e.g., the infant falls down the stairs)

Neglect, abandonment and other maltreatment syndromes

(e.g., the infant dies after being left alone for a period of time)

Assault and homicide

(e.g., the infant dies after someone harms them on purpose)

Other symptoms, signs and abnormal clinical and laboratory findings not elsewhere classified

(e.g., the infant dies of unknown cause, or unexplained heart or breathing failure)

Sudden Infant Death Syndrome (SIDS)