No, side sleeping is not safe for newborns. The only recommended sleep position for infants is on their back, placed that way every single time they go to sleep. The American Academy of Pediatrics has maintained this guidance for decades, and the shift to back sleeping in the 1990s led to a significant decline in sleep-related infant deaths. Side sleeping carries real risks, and understanding why can help you feel confident about always choosing back sleep.
Why Side Sleeping Is Dangerous
The core problem with side sleeping is instability. A newborn placed on their side can easily roll onto their stomach, which is the position associated with the highest risk of Sudden Infant Death Syndrome (SIDS). Babies lack the strength and coordination to reposition themselves if they end up face-down, meaning a simple roll can obstruct their airway.
The risk is especially severe for babies who aren’t used to being on their stomachs. Research shows that infants who normally sleep on their backs but are then placed on their side or stomach face seven to eight times the SIDS risk compared to babies who are always placed in those positions. Even occasional side placement introduces a danger that back-sleeping babies aren’t physically prepared for.
How Back Sleeping Protects the Airway
A common worry is that a baby sleeping on their back might choke if they spit up. This fear drives some parents toward side sleeping, but the anatomy actually works in the opposite direction. When a baby lies on their back, the windpipe sits above the food tube (esophagus). If the baby spits up, gravity pulls the liquid down to the lowest point, away from the airway. The windpipe stays protected. On the stomach or side, this positioning reverses, and spit-up can pool near the airway opening.
What If Your Baby Curls to the Side?
Some newborns naturally curl into a fetal position after being placed on their backs, ending up partly on their side. This is a normal reflex. If your baby shifts to the side but hasn’t rolled onto their stomach, you generally don’t need to reposition them. However, if they end up fully on their stomach, gently move them back.
The key milestone to watch for is rolling in both directions, which typically happens around four months. Once your baby can roll from back to front and front to back on their own, they can find their own comfortable sleep position and you no longer need to reposition them. Before that point, if your baby rolls to their stomach but can’t roll back yet, place them on their back again.
Sleep Positioners Are Not the Answer
Products marketed as “infant sleep positioners,” including wedges and bolsters designed to keep a baby on their side or back, are dangerous. The U.S. Consumer Product Safety Commission and the FDA issued a joint warning telling parents to stop using them entirely. Over a 13-year period, 12 infants between one and four months old died after suffocating in sleep positioners or becoming trapped between a positioner and the side of their crib. Most of these deaths occurred after the baby rolled from their side to their stomach.
The FDA has never approved any sleep positioner for preventing SIDS, and no scientific evidence supports their use for that purpose. The AAP also does not endorse them. A bare, flat, firm sleep surface with a fitted sheet is all your baby needs.
Swaddling Adds Extra Risk
If your baby is swaddled, back sleeping becomes even more critical. A swaddled baby who rolls to their side or stomach cannot use their arms to adjust their position or lift their head away from the mattress. Studies have found an increased risk of both SIDS and accidental suffocation when swaddled babies end up on their stomachs.
As soon as your baby shows any signs of trying to roll, stop swaddling completely. This applies to traditional blanket swaddles and wearable products that compress the arms and chest. A sleep sack that leaves the arms free is a safer alternative once rolling begins.
Preventing Flat Head Without Side Sleeping
Some parents consider side sleeping to prevent or address positional plagiocephaly, the flat spot that can develop on the back of a baby’s head from lying in the same position. This concern is valid, but side sleeping is not the solution. The AAP recommends two approaches instead: supervised tummy time while the baby is awake, and varying head position during back sleep (turning the head to alternate sides between sleep periods).
Positional plagiocephaly often improves on its own as babies develop and spend less time lying on the flattened area. Tummy time builds the neck and shoulder strength that helps babies hold and turn their heads, which naturally reduces pressure on any one spot.
Safe Sleep Basics
- Position: Always on the back, for every sleep, including naps.
- Surface: A firm, flat mattress with a fitted sheet. No pillows, blankets, stuffed animals, or bumper pads.
- Space: Your baby should sleep in their own sleep area, not sharing a surface with another person.
- Rolling: Once your baby can roll both ways independently, let them settle into whatever position they choose after being placed on their back.
SIDS remains the leading cause of death in infants between one month and one year of age, and sleep position is one of the most controllable risk factors. Back sleeping is a simple, consistent habit that meaningfully reduces the danger.