Place your baby on their back for every sleep, whether it’s a nap or nighttime. This single positioning choice is the most important thing you can do to reduce the risk of sudden infant death syndrome (SIDS). Since public health campaigns began promoting back sleeping in the early 1990s, SIDS rates have dropped by roughly 50%.
Why Back Sleeping Is Safest
When a baby lies on their back, the airway (trachea) sits above the esophagus. This means that even if a baby spits up, gravity helps keep liquid away from the airway. When a baby is placed on their stomach, that arrangement flips: the esophagus ends up higher than the airway and closer to the opening of the windpipe, increasing the chance of aspiration.
The risk difference is dramatic. Infants placed on their stomachs to sleep face roughly 14 times the odds of SIDS compared to those placed on their backs. Side sleeping isn’t a safe compromise either. Babies placed on their sides can easily roll onto their stomachs, which is exactly how many suffocation deaths involving sleep positioners have occurred.
When Rolling Changes the Rules
Somewhere around 4 to 6 months, most babies start rolling on their own. Once your baby can roll confidently in both directions, from back to front and from front to back, you can stop flipping them over every time they shift positions during the night. Continue placing them on their back at the start of every sleep, but let them settle into whatever position they find comfortable after that.
The key milestone is rolling both ways. A baby who can only roll one direction might get stuck face down without the strength to reposition. If your baby is showing early signs of rolling but hasn’t mastered it yet, keep repositioning them onto their back when you notice they’ve turned.
Skip the Sleep Positioners and Wedges
Products marketed as sleep positioners, including wedges, bolsters, and nests designed to keep a baby in one position, are not safe. The U.S. Consumer Product Safety Commission and the FDA issued a joint warning after 12 infants between 1 and 4 months old suffocated in or around these devices over a 13-year period. Dozens more were found in dangerous positions after being placed on their backs or sides in positioners.
The FDA has never cleared any sleep positioner to prevent SIDS, and no scientific evidence supports their use for that purpose. Even positioners marketed for reflux or flat head prevention carry suffocation risks that outweigh any potential benefit. A bare, flat, firm mattress in a crib or bassinet is the safest sleep surface.
What About Babies With Reflux?
Parents of babies who spit up frequently often worry that back sleeping increases choking risk. It actually does the opposite, thanks to the airway anatomy described above. Some older guidance suggested that babies with severe gastroesophageal reflux might benefit from stomach sleeping with the head elevated after feeding, but no recent research supports this approach. Back sleeping remains the recommendation even for babies with reflux.
Elevating one end of the crib mattress or placing a wedge under it is also not recommended. These setups can cause a baby to slide into a position that compresses the airway, and they haven’t been shown to reduce reflux symptoms during sleep.
Swaddling Safely
Swaddling can help newborns sleep more soundly on their backs by reducing the startle reflex. But it becomes dangerous the moment your baby starts showing signs of rolling. A swaddled baby who rolls face down has no way to use their arms to push up or reposition their head to breathe. This creates a direct suffocation risk.
Watch for early rolling cues: pushing up during tummy time, rocking side to side while on their back, or turning from back to side. As soon as you see these signs, transition out of any swaddle that restrains the arms. Products that convert from a full swaddle to arms-free are only safe in the arms-free configuration once rolling begins.
Preventing Flat Spots
One common concern with back sleeping is positional plagiocephaly, the flat spot that can develop on the back of a baby’s skull from consistent pressure on one area. You can minimize this without changing sleep position.
- Tummy time while awake. Start with short sessions from birth and gradually build to at least 15 to 30 minutes total per day by about 7 weeks. This strengthens neck muscles and takes pressure off the back of the head.
- Alternate crib orientation. Switch which direction you place your baby’s head in the crib each night. Babies tend to look toward the room or a light source, so changing their orientation encourages them to turn their head in different directions.
- Vary visual interest. Place toys or objects on both sides of the crib rather than directly above. This naturally prompts your baby to look left and right instead of always facing the same way.
Setting Up a Safe Sleep Surface
Positioning matters most when the sleep environment is also set up correctly. Use a firm, flat mattress that fits snugly in a crib or bassinet with no gaps around the edges. A properly firm mattress won’t conform to the shape of your baby’s face if they turn their head, which is critical for preventing suffocation. If you press your hand into the mattress and it holds the impression, it’s too soft.
Keep the sleep space bare. No pillows, blankets, stuffed animals, or bumper pads. Room sharing (keeping the crib in your bedroom) is recommended for at least the first 6 months, as it lets you monitor your baby without introducing the risks of bed sharing on an adult mattress.
The setup is straightforward: firm mattress, fitted sheet, baby on their back, nothing else in the crib. Every sleep, every time.