If you're a new parent or a parent-to-be, you've likely heard of sudden infant death syndrome, or SIDS. SIDS is the sudden and unexplained death of an infant less than 1 year of age. These deaths often occur during sleep or in the place where baby sleeps. While the risk of SIDS can be frightening for parents, there are steps you can take to keep your baby safe.
What causes SIDS in babies?
It is not known what causes SIDS. In fact, part of the definition of SIDS is that there is no known reason or cause for a baby's death. However, there are factors that can increase a baby's risk for SIDS, such as:
- Sleep position: Babies are at higher risk for SIDS when they are placed on their stomach or side for sleep, instead of being placed on their backs.
- Sleep surface: Sleeping on a soft surface, such as a soft mattress, cushioned sofa or bed with blankets and pillows, can increase a baby's risk for SIDS. It's safest for a baby to sleep alone on a firm, flat sleep surface.
- Overheating: Getting too warm when sleeping may contribute to risk of SIDS.
In addition to these sleep-related factors, certain babies may have higher risk of SIDS than others. High-risk babies may include infants who:
- Are born prematurely or with low birth weight
- Are male (SIDS is more common in boys than girls)
- Are exposed to second-hand smoke in the womb or after birth
- Had recent respiratory illness
- Have low socioeconomic status
- Have mothers who had poor prenatal care or who birthed 5 or more babies (called high maternal parity)
There is no data to support the myth that vaccines contribute to risk of SIDS.
Did a new study find the cause of SIDS?
In May 2022, a study found a link between SIDS and an enzyme called butyrylcholinesterase (BChE). In this study, researchers found strong evidence that babies who had died from SIDS had lower BChE activity compared to other infants. BChE is part of the cholinergic nervous system, which regulates certain parts of brain function.
Michelle Caraballo, M.D., Sleep Medicine Specialist at Children's Health℠ and Assistant Professor at UT Southwestern, says that while this study is exciting, there is still more to learn about preventing SIDS.
"There are still challenges that lie ahead. An association does not always mean a causation," explains Dr. Caraballo. "While this association has been found, we still need to discover if this is the definitive cause of SIDS. We also need more research to understand how to translate this information to protect at-risk babies and prevent infant deaths. It remains important for parents to continue taking the steps we know that can reduce their baby's risk."
How common is SIDS and when does the risk of SIDS decrease?
SIDS occurs in approximately 1 in 2,000 babies. Babies are at highest risk for SIDS between 2-4 months of age, and then the risk starts to decrease. After 6 months of age, the risk of SIDS is low, although SIDS can occur until they are 1 year old.
"The risk for SIDS is low in the first month of life, and then it starts to increase," says Dr. Caraballo. "The vast majority of cases occur within the first 6 months of life, but we still recommend maintaining safe sleep practices beyond 6 months since SIDS still can occur."
How to prevent SIDS
The best way to prevent SIDS is to focus on safe sleep practices. When putting your baby to sleep, always remember the ABCs of safe sleep:
- Alone: Babies should sleep by themselves in their own empty space. This means no bed-sharing with parents, and also no pillows, blankets or stuffed animals in their sleep space.
- Back: Always place your baby on their back to go to sleep or to nap. Once babies are strong enough to roll to their side or stomach, it's okay to let them stay in this position after they roll. However, start them on their back.
- Crib: Babies should sleep on a firm, flat sleep surface, such as a crib, bassinet or portable play pen (pack 'n play). The sleep surface should be covered only by a fitted sheet. Do not use crib bumpers.
The American Academy of Pediatrics advises against using inclined sleepers or any products for sleep that require a baby to be restrained. This includes a popular "Rock 'n Play" sleeper, which was recalled after being tied to sleep-related infant deaths. Don't leave a baby asleep in a car seat, as this seated position can inhibit normal breathing.
Anna Wani, M.D., a family physician with an emphasis in sleep medicine at Children's Health and Assistant Professor at UT Southwestern, adds that SIDS prevention can start even before conception.
"I recommend moms-to-be have regular check-ups with their physicians, engage in healthy lifestyle choices, and don't use substances such as drugs, alcohol and tobacco. Once your baby is born, I encourage new moms to breastfeed, which can help reduce the risk of SIDS."
Other ways to help reduce SIDS risk include:
- Allow for supervised tummy time when baby is awake to promote development
- Avoid dressing your baby too warmly for bed; specifically, it is recommended to leave baby's head uncovered
- Offer your baby a pacifier during nap and sleep time (do not attach pacifier to your baby)
How does room sharing reduce SIDS risk?
In October 2016, the American Academy of Pediatrics (AAP) updated their safe sleep guidelines to recommend room sharing with parents for baby's first year of life. Room sharing – babies sleeping on their own safe sleep surface in the same room as the parents – reduces SIDS risk and promotes exclusive breastfeeding.
Having your baby share your room – but not your bed – for at least the first six months, if not up to a year, is ideal. This allows you to monitor baby's breathing during sleep and promotes ease of breastfeeding.
"It's OK to bring your baby into bed to breastfeed, but you should put your baby back on his or her own sleep surface directly afterwards," Dr. Wani says. "As a precaution, when you bring your baby into your bed to breastfeed, make sure there isn't any loose bedding around your baby. This is to prevent suffocation in case mom falls asleep while breastfeeding and baby is still in the parents' bed."
If families choose to co-sleep or bed share, it's important to have a conversation with your baby's physician about ways to minimize risk.
Unsafe sleep practices put babies at risk. Learn simple steps to reduce the risk of SIDS through safe sleep practices from experts @Childrens.
View more resources to keep your baby safe and healthy. If you have additional questions, contact a primary care provider. They can help care for all aspects of your child's health, from well-child exams and treatment of chronic illnesses to treatment of chronic conditions.
For additional sleep-related issues in children, learn more about our Sleep Disorders Center.