Sudden infant death syndrome (SIDS) is a type of sudden unexpected infant death (SUID). SUID refers to the sudden and unexpected death of an infant under one year of age.
Other terms for SIDS include cot death or crib death. When SIDS occurs, a doctor cannot identify a reason even after an autopsy. It is often sleep-related.
The National Institute of Child Health and Human Development (NICHD) define it as “a sudden and silent medical disorder that can happen to an infant who seems healthy.”
Other types of SUID are accidental strangulation and suffocation in bed (ASSB) and death for no identifiable reason. In these cases, experts will eventually be able to identify a cause, although the cause may not be immediately clear. With SIDS, the cause remains unknown.
Every year, around 3,500 babies die suddenly and unexpectedly in the United States. In 2018, around 1,300 unexpected deaths were due to SIDS, 800 due to ASSB, and 1,300 were due to unknown causes.
Since 1990, the number of cases of SIDS has fallen steadily, but it still has a disproportionate impact on certain ethnic and racial groups.
Some factors appear to increase the risk of SIDS.
According to the Safe to Sleep safety campaign, these include:
- Race and ethnicity: SUID appears to be more common among Native American and Alaskan Native infants, followed by Black infants and non-Hispanic white infants. The lowest rates are among Hispanic, Asian, and Pacific Island infants.
- Sleep position: Sleeping on the stomach or side increases the risk. Sleeping on the back decreases the risk.
- Soft and loose bedding: This may lead to suffocation and overheating, which would increase the risk.
- Exposure to smoke: This includes maternal smoking during pregnancy and environmental exposure after birth.
- Temperature: Overheating during sleep may be a risk factor.
- Sharing a bed: Sharing a bed with an infant can increase the risk, but especially so if the bed-sharer is a smoker, is tired or has consumed alcohol, if bedding covers the infant, if there is more than one other person in the bed, or if the infant is under 14 weeks of age.
- Age: SIDS does not occur after the age of 1 year, and 90% of cases occur before 6 months.
Experts do not know what causes SIDS.
There is evidence that a problem with the nervous system may increase the risk. The problem is present at birth and may affect vital functions such as breathing, heart rate, temperature, and waking from sleep.
Scientists do not believe that these problems alone can cause SIDS, but they can increase the risk, especially when they occur with other factors.
These factors are known as The Triple Risk Model. In this model, an infant would need to have all three risk factors for SIDS to occur.
The factors are:
- Vulnerability: For example, a problem with the nervous system from birth.
- Critical developmental period: Up to the age of 6 months, rapid development may affect an infant’s susceptibility to changes such as temperature.
- An outside stressor: Sleep position, exposure to smoke, and infections are some examples.
The following guidelines from American Academy of Pediatrics (AAP) help reduce the risk of SIDS:
- Crib and mattress: Have a firm, flat sleeping area and use a safety-approved crib.
- Sleeping position: Always place the infant to sleep on their back.
- Blankets, pillows, bumper pads, and soft toys: Keep these out of the sleeping area.
- Bedding: Do not cover the infant’s head or allow them to get too hot.
Other tips that may help lower the risk include:
- Not smoking: Avoid smoking during pregnancy and do not allow smoking around the baby.
- Alcohol and recreational drugs: Avoid these during pregnancy.
- Breastfeeding: As far as possible breastfeed an infant.
- Healthcare visits: Attend all visits and appointments and get the recommended shots to prevent infections.
- Pacifiers: Give the infant a pacifier when you put them down to sleep.
- Tummy time: Give the infant tummy time during waking hours and while someone is watching them.
- Share a room but not a bed: An infant should not share a bed with anyone, including siblings and pets, but sleeping in the same room may reduce the risk.
Much remains unclear about SIDS, and this has given rise to a number of myths. Here are some answers to common questions to help dispel these myths:
Is SIDS contagious?
SIDS is not an infection, and a child cannot catch it, but having an upper respiratory infection may increase the risk in those who are susceptible.
Will sleeping on the back lead to choking?
When babies vomit or cough up fluid, a special reflex enables them to expel or swallow it, so they are unlikely to choke on any fluid that comes up during sleep.
Do cribs cause SIDS?
A crib cannot cause SIDS, but an unsuitable sleeping environment can increase the risk.
Can we prevent SIDS?
There are ways of reducing the risk, but it is not possible to prevent SIDS. It is not the result of neglect or child abuse.
Do vaccines cause SIDS?
Vaccines can protect infants from infections that may increase the risk. Following the scheduled vaccination program and attending all health visits can help keep the baby safe.
Isn’t it safer to share a bed?
Sharing a room is safe, but sharing a bed is not, as there is a higher risk of suffocation and overheating.
When SIDS occurs, an infant under the age of 1 year dies suddenly, and it is not possible to identify a reason.
Experts are still investigating why it happens, but various factors appear to reduce the risk.
Following safe sleeping practices, preventing exposure to smoke, and following vaccination schedules are all ways of lowering the risk of SIDS.