The first rule of safe baby sleep 101 is that you should always, always place your baby to sleep on his back from the moment he’s born to prevent sudden infant death syndrome (SIDS).
Still, it’s no secret that babies sometimes fuss when they’re on their backs. And if you've ever watched tummy time spontaneously turn into naptime, you might have noticed your baby seems more content sleeping on his stomach.
Indeed, belly sleeping seems to be the preferred position for many babies. Little ones may be less likely to startle and wake themselves up — possibly because it feels more secure and cozier snuggling up against the mattress.
But even though your baby might be more comfortable sleeping on his tummy, it isn’t safe until he’s strong enough to roll himself onto his stomach. Here’s why it’s so important for your baby to sleep on his back, plus tips to encourage back sleeping.
Baby Nursery FAQs
Infants usually placed on their backs or sides were at the lowest risk for SIDS. Infants placed face down were at a fourfold increased risk of SIDS. But those infants usually placed on their backs who were placed on their stomachs for the last sleep were 18-times more likely to die of SIDS than the first group.
The simple act of placing infants on their backs to sleep significantly lowers SIDS risk. As stomach sleeping has declined in response to back-sleeping campaigns worldwide, statistics show that the contribution of side sleeping to SIDS risk has increased.
As we mentioned, the guidelines recommend you continue to put your baby to sleep on their back until age 1, even though around six months old — or even earlier — they'll be able to roll over both ways naturally. Once this happens, it's generally OK to let your little one sleep in this position.
Myth: Babies who sleep on their backs will choke if they spit up or vomit during sleep. Fact: Babies automatically cough up or swallow fluid that they spit up or vomit—it's a reflex to keep the airway clear. Studies show no increase in deaths from choking among babies who sleep on their backs.
Always place your baby on their back to sleep, not on the stomach or side. The rate of SIDS has gone way down since the AAP introduced this recommendation in 1992. Once babies consistently roll over from front to back and back to front, it's fine to remain in the sleep position they choose.
Back Sleeping And SIDS
The single most effective action that parents and caregivers can take to lower a baby's risk of SIDS is to place the baby to sleep on their back for naps and at night.
Compared with back sleeping, stomach sleeping increases the risk of SIDS by 1.7 - 12.9. The mechanisms by which stomach sleeping might lead to SIDS are unknown. Studies suggest that stomach sleeping may increase SIDS risk through a variety of mechanisms, including:
- Increasing the probability that the baby re-breathes their own exhaled breath, leading to carbon dioxide buildup and low oxygen levels
- Causing upper airway obstruction
- Interfering with body heat dissipation leads to overheating.
Whatever the mechanism, evidence from numerous countries—including New Zealand, Sweden, and the United States—suggests that placing babies on their backs to sleep results in a substantial decline in the SIDS rate compared to placing babies on their stomachs to sleep.
Researchers have established the link between stomach sleeping and SIDS by showing that babies who died from SIDS were more likely to be put to sleep on their stomachs compared to babies who lived.
After that discovery, public health campaigns were launched to promote back sleep position and reduce the use of the stomach sleep position. Dramatic decreases in SIDS rates were observed in all countries with these public health campaigns; these campaigns have successfully reduced the prevalence of stomach sleep among infants. In areas where stomach sleeping is rare (including Hong Kong), SIDS rates historically have been very low, which further strengthens the association.
Compared with infants who sleep on their backs, infants who sleep on their stomachs:
- Are less reactive to noise
- Experience sudden decreases in blood pressure and heart rate control
- Experience less movement, higher arousal thresholds, and longer periods of deep sleep.
These characteristics might put an infant at higher risk of SIDS. The simple act of placing infants on their backs to sleep significantly lowers SIDS risk.
As stomach sleeping has declined in response to back-sleeping campaigns worldwide, statistics show that the contribution of side sleeping to SIDS risk has increased. Research shows that side sleeping is just as risky as stomach sleep position and, therefore, should not be used.
Placing babies on their backs to sleep is not associated with risks for other problems. For example, there is no increase in aspiration or complaints of vomiting when babies are placed on their backs to sleep.
Moreover, babies may benefit in other ways from sleeping on their backs. A 2003 study found that infants who slept on their backs were less likely than infants who slept on their stomachs to develop ear infections, stuffy noses, or fevers.
Several studies found that back sleepers have delayed early motor skill milestones. However, one recent Israeli study found no difference in gross motor developmental skills at six months among supine (back) and prone (stomach) sleepers.
Some studies have noted that even though supine sleepers experience these early delays, there is no significant age difference in terms of when the infants learn to walk.
Multiple studies have found a positive correlation between the amount of time supine sleepers spend prone during their awake hours and motor skills development. This finding reinforces the need to educate parents about the importance of tummy time.
Why Back to Sleep is the Safest Position for Your Baby
Key Points on why Back to Sleep is safest:
- Always place the baby on the back to sleep and not on the tummy or side. There is an increased risk of sudden unexpected death for babies when they sleep on their tummies, and there is a danger of rolling to this position if they are sleeping on their sides.
- Babies must always be placed on the back to sleep. Babies usually sleeping on the back and are placed on the tummy or side for the first time are at an increased risk of sudden unexpected death.
- Once a baby has been observed to repeatedly roll from back to front and back again on their own for several weeks, they can be left to find their preferred sleep position (this is usually around 5-6 months).
- At the critical time of starting to roll, the sleep environment must remain safe
- Babies that can roll should no longer be wrapped
- Babies born preterm should be slept on the back as soon as they are medically stable (out of oxygen).
How to get a baby to stop sleeping on his side
If it seems like your newborn can’t sleep comfortably on his back, he’s not alone. Many babies seem to feel more secure sleeping on their bellies or sides.
If that’s the case, there are things you can do to try to keep your baby both happy and safe while he rests. From the day you bring him home, try these strategies for getting your baby to sleep on his back (and keep him in that position!).
Swaddle your baby
A cozy burrito-style wrap will help give your baby the security he’s craving from sleeping on his tummy. Swaddling with a blanket is easy once you get the hang of it, but you can also sidestep the folding and tucking altogether by opting for a zipper or Velcro swaddle wrap.
A few important tips to keep in mind for safety: Make sure your baby’s room is cool enough to be comfortable in the extra layers since overheating is another risk factor for SIDS.
Also, know that you’ll need to ditch the swaddling blanket (or switch to a swaddle-sack hybrid or a sleep sack, which can’t be kicked off) as soon as your baby shows signs of trying to roll. That typically happens around ages 3 to 4 months, but it can be as young as two months for some babies, so it's safest to stop swaddling when you are around two months old.
Offer a pacifier
Give your baby a binkie when you put him down for his nap or sleep at night. Having something to suck on can be soothing, plus it’s harder for babies to keep pacifiers in their mouths if they roll onto their tummies or sides, so it's a tactic that often works well at keeping them sleeping on their backs.
Skip the positioner
Steer clear of wedges, rolled up blankets or other positioners placed on your baby’s mattress. Even though some of these products might prevent SIDS, they pose a serious suffocation risk.
Ease him into it
Train your baby to be more comfortable sleeping on his back by rocking him until he's drowsy, then transferring to the crib and putting him down on his back.
Stick with it
Consistency is key when it comes to any sleep routine. So while it might take some time and persistence, even if it seems like your newborn won’t sleep on his back, eventually, he’ll get used to the position — especially if he’s never known another way to sleep.
Know when to call the doctor
Most babies adjust to sleeping on their backs, even if they aren’t big fans at first. But talk with the pediatrician if your baby fusses every time you put him to sleep on his back. It’s rare, but there are some physical and anatomical reasons a baby may be uncomfortable sleeping on his back that your pediatrician should rule out first.
Concerns about back sleeping
Risk of aspiration or choking
Some parents and health professionals have expressed concern about back sleeping and the risk of a baby choking in this position. However, careful study of the baby's airway has shown that healthy babies placed to sleep on the back are less likely to choke on vomit than prone or tummy sleeping babies.
In the supine position, the upper respiratory airway is above the oesophagus (digestive tract). Therefore, regurgitated milk ascending the oesophagus is readily swallowed again such that aspiration into the respiratory tract is avoided.
When the baby is placed on the tummy, the oesophagus sits above the baby’s upper airway. If the baby regurgitates or vomits milk, it is relatively easy for the milk or fluid to be inhaled into the baby’s upper airway leading to micro-aspiration and stimulating receptors and cessation of breathing (apnoea). Several studies have shown that the risk of aspiration is not increased by supine sleeping.
There is often particular concern regarding aspiration in babies with gastro-oesophageal reflux. The AAP supports the recommendations of the North American Society for Pediatric Gastroenterology and Nutrition, which recommends that babies with gastro-oesophageal reflux be placed in the supine position to sleep.
In babies with particularly rare medical conditions for whom the risk of death from gastro-oesophageal reflux is greater than the risk of SIDS, medical practitioners may provide specific advice on sleeping positions.
Elevating the head of the cot while the baby is sleeping supine is not effective in reducing gastro-oesophageal reflux.34-35 In addition, elevating the cot can result in the baby sliding underneath the bedding and is not recommended.
Pillows or positional devices that position the baby with an elevation and are often marketed for baby reflux are not recommended due to suffocation risks and lack of evidence supporting efficacy.
An increase in skull deformity (deformational plagiocephaly and craniosynostosis) requiring treatment has been reported since the Back to Sleep campaign. This is reported to be related to the concern that parents had in placing their baby on their tummy at any time, resulting in babies spending long periods on their back.
To reduce the likelihood of skull shape problems, parents are encouraged to place babies prone for ‘tummy time’ from birth when babies are awake and under direct supervision.
However, another earlier study demonstrated no significant relationship between prone sleeping and the development of plagiocephaly; the baby’s positional preference and baby care practices used by parents, including the frequency of supervised tummy time, played a greater role.
[For further information about positional plagiocephaly and tips for tummy time, see Baby’s Head Shape]
My baby sleeps longer and more deeply on their tummy.
Many parents and grandparents report that the baby appears to sleep longer when on the tummy. This is thought to be due to reduced arousal responses. However, arousal and swallowing mechanisms are needed to protect the baby's airway and work best when a baby is placed to sleep on the back.
The back sleeping position is best for newborn babies.
Some health professionals and parents continue to place newborn babies on the side immediately after birth to believe that they need to clear their airway of amniotic fluid and are less likely to aspirate when in the side position.
There is no evidence that fluid is more readily cleared in the side position. Babies should be placed on the back as soon as they are ready to be placed in the cot or bassinet. Parents must observe health professionals placing babies in the supine position as they are more likely to model this practice when they go home.
The back sleeping position is best for preterm babies.
Preterm babies are at increased risk for SUDI, including SIDS, compared to full-term babies.
Studies in the UK and New Zealand have reported that at least four times as many SIDS infants were born preterm compared to control infants who did not die (20% compared to 5%), and these proportional differences have remained unchanged since the introduction of public campaigns for reducing the risks.
The association between the prone sleeping position and SIDS among low birth weight babies is equal to or stronger than in babies born at term.
It has been suggested that if the mothers of preterm or low birth weight infants followed the safe sleeping recommendations and all placed their infants supine in a cot by the parental bed, this would potentially reduce the overall SIDS rate by a further 20%.
Preterm babies are frequently placed prone as this position is thought to improve respiratory function and reduce energy requirements. It is common practice for babies requiring intensive care to be placed in the prone position during their acute illness.
In one survey, approximately 95% of neonatal intensive care unit (NICU) nurses identified a non-supine position as the best sleep position for preterm babies. This study reported that nurses believed prone sleeping was beneficial for respiratory associated complications, such as upper airway anomalies and respiratory distress, and non-respiratory complications, such as reflux and inconsolability.
However, likely, these improvements are simply due to babies spending more time in quiet sleep and less time in active sleep, a state associated with increased apnoeas and increased arousability.
The current recommendation is that preterm babies are placed supine as soon as clinically stable, i.e. out of oxygen, and as early as possible before discharge from the hospital so that their parents are used to them sleeping in this position and are supported with settling their babies in the back sleeping position.
Likely protective mechanism of back sleeping
Body position during sleep significantly modifies both the spontaneous and induced arousals in preterm and term babies, with babies being significantly less arousable when slept prone. Indeed, it is this perceived deeper sleep that reinforces parents’ tendencies to prefer sleeping the baby in the prone position.
Some studies have identified that babies sleep longer in the prone position and have increased quiet sleep, a state of reduced arousability.42 The prone sleeping position is associated with higher central and peripheral body temperatures when compared to the prone position.
Cardiovascular control is also significantly altered in the prone sleeping position in preterm babies. Compared to the supine sleeping position, heart rate in the prone position is increased during sleep in both term and preterm babies.
Studies investigating heart rate variability, a measure of autonomic control of heart rate, have found that at both 1 and 3 months postnatal age, overall heart rate variability is decreased in the prone position during sleep in both term and preterm babies, suggestive of poor autonomic control in the prone sleeping position.
It has been suggested that a reduction in parasympathetic control caused by an increase in peripheral skin temperature in the prone position may underlie the change in heart rate variability.65 Several studies have found that the sympathetic effects on blood pressure and vasomotor tone decrease in the prone sleeping position.
Lower resting blood pressure and altered blood pressure responses, and decreased vasoconstrictor ability59 to head-up tilting has been identified in term babies when sleeping in the prone position compared with the supine position.
The prone position has also been associated with lower cerebral oxygenation in healthy term babies, a finding which may underpin the reduced arousal responses in this position.
Studies have also shown that swallowing and arousal, which are essential airway protection mechanisms, are also impaired in the prone position during active sleep and were improved in the supine position.
When challenged with simulated reflux or postnasal secretions, breathing rate was significantly reduced when infants slept pronely.
The prone or back sleeping position is the safest position for babies to sleep for the first 12 months.
Consistency is the best technique to get your baby to sleep on their back. Swaddling your baby can help them feel more secure, which is one of the things they seek when they roll onto their stomach. Use a swaddling blanket until your baby is old enough to remove it independently.
Once this happens, which could be as early as two months old, you can use a sleeping sack meant for babies, which they won't be able to take off.
To help your baby sleep on their back, try rocking them in your arms before placing them in their crib. If your baby falls asleep in their car seat, sling, stroller, or any other surface, make sure you place them in their crib as soon as possible. The crib should have a firm mattress and fitted sheet.