Sudden infant death syndrome (SIDS)
What is SIDS?
Sudden infant death syndrome (SIDS) is the unexplained death of an infant during sleep. Because SIDS typically occurs during sleep at night, when infants are in their cribs, it’s also known as “crib death.” SIDS is often diagnosed during an autopsy when another cause of death can’t be found from the death scene investigation or review of the infant’s medical history.
- SIDS is the leading cause of death for infants between 1 and 12 months old.
- 90 percent of SIDS deaths are for infants younger than 6 months.
- About 1,600 American infants die from SIDS each year, and another 900 die from accidental strangulation or suffocation while asleep.
You may have heard SIDS referred to alternately as SUID. SUID stands for Sudden Unexpected Infant Death, and refers to all sudden infant deaths. SUID includes SIDS, accidental infant deaths (e.g. from suffocation or strangulation), sudden natural deaths (e.g. from infections, neurological conditions, cardiac disorders), and infant homicides. All SIDS deaths are also SUID, but it does not work the other way around. Approximately 3500 infants die from SUID each year in the United States.
Once babies are one year old, they’re no longer at risk of SIDS.
What causes SIDS?
Researchers still do not know what causes SIDS. The current theory is that SIDS may be caused by abnormalities in the infant’s brain related to breathing during sleep, combined with other physical and environmental risk factors.
Physical and environmental factors that can put an infant at higher risk of SIDS include:
- Brain abnormalities
- Low birth weight
- Respiratory infection
- Sleeping on the stomach or side, on a soft surface, or with parents
Physical SIDS risk factors
The first three factors in this list are physical, and describe circumstances that put an infant’s ability to breathe properly at risk. Brain abnormalities related to SIDS describe an infant with a brain not yet fully matured or with reduced capability regarding the breathing and arousal functions during sleep. Specifically, the brain chemical serotonin may be involved in SIDS. Serotonin helps the brain regulate breathing during sleep, and 70 percent of SIDS cases involve infants with lower-than-normal levels of serotonin.
Many infants who die of SIDS are premature or have a lower birth weight due to multiple births (twins, for instances, have twice as high a risk of SIDS). In these infants, the portion of the brain that controls the body’s breathing and arousal during sleep isn’t mature enough to work as it should. Infants are also at risk of SIDS if they currently have or recently had a cold, which may interfere with their breathing.
Environmental SIDS risk factors
Sleeping position and environment also make an infant more vulnerable to SIDS. When an infant is lying face down, or placed on their stomach or side to sleep, it’s much more difficult for them to breathe. The effect is worsened if the sleeping surface is soft, as with a super soft comforter, waterbed or blanket. The infant can sink further down into the surface and increasingly block their airway. Instead, multiple authorities such as the CDC and American Academy of Pediatrics recommend that infants sleep on their backs.
Parents can also present soft surfaces and obstacles that block infant’s airways. While infants who sleep in the same room as their parents have a lower risk of SIDS due to the parents being able to more closely monitor their sleep, the reverse is true if the infants sleep in the same bed as their parents.
Demographical SIDS risk factors
Researchers have also identified several trends among infants who died from SIDS. Researchers aren’t sure if these risk factors are correlative or causative. The following conditions may also increase a baby’s risk of SIDS:
- Males are more likely to die from SIDS than females (60% vs 40%).
- Infants are at highest risk during the age of 2 to 3 months old.
- Black, American Indian, and Alaska Native infants are 2 to 3 times likelier to die from SIDS than Caucasian children.
- Infants are at higher risk if there is a family history of SIDS.
- Infants exposed to secondhand smoke are at higher risk of SIDS.
- Cases of SIDS are higher during winter months.
There are also factors related to the birth mother that correspond to a higher risk of SIDS in the child. If the mother is younger than 20, has poor prenatal care, and uses drug, alcohol, or tobacco, her infant has a higher risk of developing SIDS.
Why is stomach sleeping so dangerous for infants?
Stomach sleeping can block an infant’s airway and interfere with their breathing. It also increases the opportunity for rebreathing, which occurs when an infant breathes back in their own exhaled air due to close quarters with a soft mattress, bedding, pillow, or toys near their face. Rebreathing is dangerous because it reduces the level of oxygen in the infant’s body while simultaneously increasing the level of carbon dioxide.
Researchers believe the brain abnormalities in infants who die from SIDS relate to the brain’s ability to control breathing and waking during sleep. In a healthy infant, their brain will wake them up and cause them to cry if they are not getting enough oxygen during sleep. In an infant with SIDS-related brain abnormalities, it’s possible the brain doesn’t detect the reduced oxygen and continues to allow the baby to sleep.
Because infants sleeping on their side are likely to roll onto their stomachs, side sleeping is also not recommended for infants under 1 year old.
Flat head syndrome
Positional plagiocephaly, commonly known as “flat head syndrome,” describes the flat spot some infants develop on the back of their heads.
Parents can protect their infant from SIDS while also avoiding flat head syndrome from too much time lying on their back, by giving their infant supervised “tummy time” when they are awake. Parents can also prevent flat head syndrome by holding or cuddling with their baby upright whenever they’re not sleeping, and limiting the amount of time spent in car or baby seats and carriers.
The Back to Sleep and Safe to Sleep campaigns
The American Academy of Pediatrics (AAP) has been at the forefront of SIDS research and prevention. As evidence grew to support the link between stomach sleeping and SIDS, the AAP launched the Back to Sleep campaign in 1994 encouraging parents to have infants younger than 1 year old sleep on their back.
Under the new name of the Safe to Sleep campaign, the AAP continues to encourage best practices around providing a safe sleep environment for infants that reduces their risk of SIDS.
How to reduce the risk of SIDS
If there is any good news about SIDS, it’s that greater awareness has led to fewer deaths from SIDS. The rate of SIDS has dropped more than 60% over the past 25 years, according to the CDC. In fact, their latest numbers from 2015 report 39.4 deaths per 100,000 live births, compared to 154.5 deaths in 1990.
While the cause of SIDS is still unknown, following best practices for prevention can significantly lower an infant’s risk of SIDS. Parents and childcare providers should adhere to the following SIDS prevention guidelines.
1. Always place your infant on their back to sleep.
An infant is at higher risk of SIDS if they sleep on their stomach or their side. In these sleeping positions, their face is likelier to be smothered by the mattress or bedding and block their airway. Always place your infant on their back whenever he or she goes to sleep, and if your child falls asleep in something other than their bed (stroller, car seat, baby seat), get them out and lay them down on a flat surface on their back. Sleeping in the upright position for a prolonged period of time encourages your baby’s head to roll forward, which puts them at greater risk of suffocation.
The chart below shows the strong correlation between a higher percentage of children sleeping on their backs and fewer infant deaths from SIDS.
Your child should always sleep on their back. In fact, allowing them to sleep on their stomach or side occasionally actually puts your child at greater risk of SIDS if they usually sleep on their back in the recommended position. Some parents worry their child will choke if they sleep on their back, but this is misguided. Choking is extremely rare in healthy sleeping infants, who will swallow or cough up fluids as needed.
Once your child is 6 months or older, they may roll over of their own accord. That’s fine once they’ve reached this age, but you should continue initially placing them on their back until they reach 1 year of age.
2. Don’t use soft bedding and materials in the infant’s sleep environment.
Prevent smothering and suffocation by using a firm mattress in your infant’s crib or bassinet with only a fitted sheet.
Avoid memory foam mattresses and mattress toppers. Do not put additional blankets, toys, or crib bumper pads in the baby’s cribs as these can block your infant’s airways. Instead, ensure your child is properly clothed with pajamas for comfort.
3. Don’t sleep in the same bed as your infant.
You should keep your baby close so you can monitor them, but they should sleep in a separate bed. Allowing your baby to sleep with you or someone else in the same bed, couch, chair, or furniture increases the soft surfaces your infant comes into contact with, and thus their risk of SIDS from suffocation.
It’s not just the other person’s body that poses a suffocation risk to infants. Adults and siblings are likelier to sleep with additional bedding and pillows, all of which present additional suffocation risks to infants. Plus, adults are likelier to drink, smoke, or use sleep medication. Secondhand smoke can impair the infant’s health by interfering with their oxygen. Other substances adults use can impair their judgment, or prevent them from waking during sleep, either of which is problematic if they roll over onto the child or aren’t roused by irregular breathing or movement from the infant.
4. Breastfeed your infant.
Breastfeeding can reduce your baby’s SIDS risk by 50 percent. Researchers still aren’t sure why. It may be something in the breast milk itself, or the skin-to-skin contact that encourages healthy development in your baby.
If you’re ever tired while breastfeeding, avoid doing it sitting down so as to avoid falling asleep with your baby in an unsafe position.
5. Immunize your infant.
Infants who have followed the AAP’s routine recommendations for infant immunizations are half as likely to develop SIDS as infants who haven’t been fully immunized.
6. Use a pacifier to help your infant fall asleep.
Using a pacifier to sleep is associated with a lower risk of SIDS. Put the pacifier in your infant’s mouth when you put them to bed, but don’t put it back in once they fall asleep. Other best practices for pacifier use include:
- Don’t start using a pacifier until your infant has been breastfeeding regularly for at least 1 month so as to avoid nipple confusion or preference for the pacifier over the mother.
- Don’t force your infant to use the pacifier if they don’t want to.
- Keep your pacifier clean and don’t coat it with any substance.
- Replace your pacifier if the nipple is damaged.
7. Prevent your infant from overheating.
Overheating during sleep increases an infant’s risk of SIDS. You can easily tell if your child is overheating if they are sweating or hot to your touch.
Clothe your child in comfortable pajamas and keep the bedroom at a comfortably cool temperature. If you think it’s comfortable, your child probably will, too. If you’re worried about your child getting cold, do not put a blanket in the bed (see tip #2 above). Instead, dress your infant in onesie pajamas or put them in a wearable blanket or sleep sack.
If you swaddle your baby, take special care to ensure he or she doesn’t overheat, and never place your baby face down while swaddled.
8. Avoid alcohol, drug, and tobacco use during pregnancy and after birth.
Infants of mothers who use alcohol, drug and tobacco during pregnancy can have premature births and a higher risk of SIDS. After birth, secondhand smoke is linked to higher SIDS risk. Alcohol and drug use can impair mental capacity and reduce inhibitions, so parents may not use their best judgment around their child or when putting them to bed, which can increase their SIDS risk.
9. Avoid products that claim to reduce SIDS.
Many manufacturers claim that their products reduce SIDS as a marketing ploy, including cardiac monitors and electronic respirators and breathable mattresses. However, none of these have been found to actually work, so avoid companies that are willing to claim keeping your baby safe in order to sell you their products.
10. Avoid honey in your infant’s diet.
Honey can cause botulism in children under 1 year old, and researchers believe the bacteria from botulism may be linked to SIDS.
11. Receive early and regular prenatal and postnatal care.
Good prenatal care can help prevent premature births which are linked to SIDS.
Regular postnatal care keeps your baby safe and helps make you aware of any conditions that may put your baby further at risk of SIDS. In these situations, your doctor can recommend additional things you can do to reduce your child’s risk or better monitor their sleep.
12. Educate other caregivers about proper sleeping position and SIDS prevention practices.
As many of 20 percent of SIDS cases occur in a daycare setting, which is why you should make sure anyone who watches your child for a prolonged amount of time is educated on SIDS risk factors and recommended prevention practices. This includes caregivers, daycare workers, siblings, grandparents, and other relatives and friends.
What is co-sleeping?
Co-sleeping refers to bed-sharing situations where an infant sleeps in the same bed as their parent(s). Co-sleeping is common practice in attachment parenting. Co-sleeping typically begins when a child is an infant and continues until about age 3 or 4. However, co-sleeping may also be used as a broad term to describe the following sleeping arrangements:
- Bed-sharing and family bed arrangements where parents sleep in the same bed with their infant
- Separate-surface co-sleeping or sidecar arrangements where one side of the infant’s crib is securely attached to the mother’s side of the bed
- Room-sharing where the infant’s crib or bassinet is in the same room as the parents’ bed
For the purposes of this guide, we will use the most common used definition where co-sleeping refers to bed-sharing and family bed arrangements.
Pros and cons of co-sleeping
Co-sleeping has gained popularity in recent years but remains a controversial issue.
While some experts believe that bed-sharing allows a parent to respond more quickly to a baby’s breathing or movements, no definitive studies have been done to show it helps lower an infant’s risk of SIDS. In fact, prominent organizations like the American Academy of Pediatrics advise against co-sleeping particularly because of the link with increased risk of SIDS.
Proponents of bed-sharing often point out that co-sleeping is used interchangeably by antagonists to refer to all types of co-sleeping, from the significantly more dangerous co-sleeping on a couch to that on a bed. They also point out that co-sleeping while breastfeeding is the norm in Japan, where the rates of SIDS are lowest in the world. Infant mortality rates in Japan are 2.8 per 1,000 live births. By comparison, infant mortality rates in the U.S. are much higher at 6.2.
There is also historical precedent for co-sleeping. For much of our history, and still in many cultures around the world today, children share a bed with their parents. It wasn’t until the second half of the 19th century that European and North Americans started separating children from parents and developing a cultural ideal around privacy and bedtime.
Some bed-sharing parents feel more secure having their children closeby, and believe it reduces separation anxiety for the child. On the other hand, many parents want to encourage their child developing a separate identity early on, and wish to reserve their bed for adults only.
Many of the touted benefits of bed-sharing revolve around facilitated nighttime breastfeeding. However, it is important to note that it is the nighttime breastfeeding itself, and not the co-sleeping, that contributes to healthy infant development. Regular nighttime breastfeeding increases the mother’s prolactin levels (the milk producing hormone). Breastfed babies grow faster and have a significantly lower risk of SIDS than bottle-fed babies. Studies show that nighttime breastmilk contains higher levels of both human growth hormone and melatonin which foster healthy development and promote good sleep, respectively. Breastfeeding also reduces the risk of postpartum depression and helps mothers sleep better.
Benefits of co-sleeping
- Parents and infants may both get more sleep, since minimal time is spent traveling to the infant’s bed. Sleep deprivation from infant nighttime awakenings can result in irritability and other issues that can lead to marital conflict.
- Nighttime feeding is more convenient for nursing mothers and takes slightly less time.
- Mothers can have an easier time getting their sleep cycle in sync with their child’s.
- The infant experiences less separation anxiety due to proximity of the parents.
- Parents can feel a better sense of intimacy with their infant.
- Skin-to-skin contact is important for healthy baby development. Similarly, sleeping side-by-side can synchronize the heartbeat and breathing rates of a mother and her infant, promoting healthy respiratory development.
- Co-sleeping may prevent or reduce severity of postnatal depression.
Risks of co-sleeping
- The AAP posits bed-sharing is the greatest risk factor for SIDS. In a 2014 report, 69 percent of infants who died from SIDS were bed-sharing at the time of death.
- While some parents may feel they get more sleep from wasting less time traveling to their infant’s bed during the night, that effect may be counteracted by more frequent awakenings due to harmless noises babies make during the night, such as burping.
- Parents who co-sleep may find it more challenging to have regular sex.
- Children who co-sleep are likelier to have poorer sleep habits and chronic sleep issues than those who don’t, according to research by the Norwegian Institute of Public Health.
- Bed-sharing infants may have a tougher time transitioning to a crib or bed later on or sleeping at all without a parent by their side. A 2017 study in Pediatrics found that infants who room-share or bed-share beyond four months get less sleep and experience more interruptions during sleep than infants who get their own room by that age.
Creating a safe co-sleeping environment
If you choose to practice co-sleeping with your infant, the following guidelines will help ensure your child’s safety during sleep:Always put your infant down to sleep on their back. The risk of SIDS increases when a child sleeps on their stomach or side.
- Use a firm sleep surface with a tight-fitting bedsheet. Soft mattresses like memory foam or waterbeds pose a suffocation risk to your infant.
- Refrain from having additional bedding, pillows, blankets, or soft toys on the bed. If your child’s face rolls into one of these surfaces, they may suffocate.
- Get rid of any space between the mattress and the bedframe or the bed and the wall. This helps keep your baby from rolling off onto the floor or getting trapped against the wall or bed.
- Do not sleep with your baby on a couch or other piece of furniture. They may roll from their intended position and get stuck on the sides where they’re at greater risk of suffocation.
- Position your baby by the mother. Do not have other children sleep with babies less than 1 year old.
- Prevent your baby from overheating. Keep the bedroom at a cool temperature and do not swaddle your baby.
- Do not sleep with your baby if you smoke or if you have recently used alcohol, drugs, or sedatives. Secondhand smoke increases your child’s risk of developing SIDS, and other substances can impair your awareness during sleep.
- Take care of other bodily hazards. If you have long hair, put it in a bun so that it doesn’t accidentally wrap around your infant’s neck and strangle them. Take off jewelry and check bedding for any stray threads that may wrap around an infant’s neck, finger, or toe and cut off circulation or strangle them. If either parent is obese or a very deep sleeper, avoid co-sleeping or have them sleep in a different bed. Similarly, if your baby is premature, had a low birthweight, or is less than 3 months old, you should avoid bed-sharing. These individuals may find a suitable middle ground with sidecar arrangements and co-sleeper cribs.