The safest way for a baby to sleep is alone, on their back, on a firm and flat surface with nothing else in the sleep space. That means no blankets, no pillows, no stuffed animals, and no bumper pads. This setup dramatically lowers the risk of sudden infant death syndrome (SIDS) and other sleep-related causes of infant death, which together account for roughly 3,500 deaths in the United States each year.
Why Back Sleeping Matters
Babies who sleep on their stomachs or sides have twice the risk of dying from SIDS compared to babies placed on their backs. Back sleeping is the single most important thing you can do to protect your baby during sleep, and it applies to every nap and every nighttime stretch for the entire first year of life.
Some parents worry that babies sleeping on their backs might choke on spit-up, but healthy infants have reflexes that naturally clear their airway. Back sleeping is safer even for babies with reflux. Once your baby can roll both ways on their own, you don’t need to reposition them if they flip during sleep, but always place them on their back to start.
The Right Sleep Surface
Your baby’s mattress should be firm and flat. A good test: when your baby lies on it, the mattress shouldn’t conform to the shape of their head or body. Crib mattresses sold in the United States must pass a federally mandated firmness test under standards set by the Consumer Product Safety Commission (CPSC). Full-size crib mattresses, portable crib mattresses, and play yard mattresses are all tested to the same firmness standard.
Inclined sleepers, which were once popular products, are now banned. The Safe Sleep for Babies Act, signed into law in 2022, made it illegal to sell any infant sleeper with an incline greater than 10 degrees. These products were linked to dozens of infant deaths because the angle allowed babies to slump into positions that cut off their airway. If you have an older inclined sleeper at home, stop using it. The same law also banned crib bumpers nationwide.
Approved sleep surfaces include a crib, bassinet, portable crib, or play yard that meets current safety standards. Adult beds, couches, recliners, and armchairs are never safe sleep surfaces for a baby. Falling asleep while holding your baby on a couch or recliner is one of the most dangerous scenarios for infant suffocation.
Keep the Crib Bare
The CPSC puts it simply: “Bare is best.” The only thing that belongs in your baby’s crib is a fitted sheet. Many young babies cannot lift their heads to pull away from soft objects near their face, which means even a thin blanket or a small stuffed animal can become a suffocation hazard.
Items to keep out of the sleep space:
- Blankets and quilts, including lightweight receiving blankets
- Pillows of any size
- Crib bumpers, including mesh versions
- Sleep positioners and wedges
- Stuffed animals and toys
- Loose bedding of any kind
If you’re worried about your baby getting cold, use a wearable blanket (sometimes called a sleep sack). These stay securely on your baby’s body and can’t ride up over the face.
Room Sharing Without Bed Sharing
Placing your baby’s crib or bassinet in your bedroom cuts the risk of SIDS by as much as 50% compared to having the baby sleep in a separate room. The American Academy of Pediatrics recommends room sharing for at least the first six months, and ideally through the first year. Sleep-related deaths are highest in the first six months, which is why that window is especially important.
Room sharing is not the same as bed sharing. When all bed-sharing situations are analyzed together, the risk of a sudden sleep-related death is nearly three times higher than room sharing without bed sharing. A baby in your room but on their own firm, flat surface gets the protective benefit of your proximity (you’re more likely to notice and respond to changes) without the suffocation risks that come with sharing an adult mattress, pillows, and blankets.
Room Temperature and Overheating
Overheating is an independent risk factor for SIDS. The ideal room temperature for a sleeping baby is between 68 and 72°F (20 to 22°C). Dress your baby in one layer more than you’d wear comfortably in the same room, and skip hats indoors since babies release excess heat through their heads.
To check if your baby is too warm, touch the back of their neck. If it feels sweaty or hot, remove a layer. Flushed skin and unusual fussiness are also signs of overheating. It’s generally safer to err on the slightly cool side rather than the warm side.
Swaddling Safety
Swaddling can help newborns sleep more soundly by dampening the startle reflex, but it comes with a hard deadline. You must stop swaddling as soon as your baby shows any signs of rolling over. For many babies, this happens around two to four months, but some start earlier.
Signs it’s time to stop swaddling include: pushing up on their hands during tummy time, lifting their legs and flopping them to one side, breaking free of the swaddle, or any rolling motion during play. A swaddled baby who rolls onto their stomach cannot use their arms to push themselves back or clear their face from the mattress, which creates a serious suffocation risk. Transitioning to a sleep sack with arms free is a safe next step.
While your baby is still being swaddled, always place them on their back. A swaddled baby should never be placed on their side or stomach.
Pacifiers at Bedtime
Offering a pacifier when you put your baby down to sleep is associated with a lower risk of SIDS. Multiple observational studies dating back to the early 1990s have found this connection, and the AAP recommends pacifier use at sleep time throughout the first year. One proposed explanation is that the sucking motion helps keep the airway more open and may aid in clearing reflux during sleep.
A few practical points: you don’t need to put the pacifier back in once your baby falls asleep and it drops out. Don’t coat it in anything sweet. If you’re breastfeeding, it’s generally best to wait until breastfeeding is well established, typically around one month, before introducing a pacifier. And if your baby refuses it, that’s fine. Don’t force it.
Putting It All Together
Safe sleep comes down to a consistent routine every single time your baby sleeps, whether it’s a five-minute car seat nap that you transfer to the crib or a full night’s rest. Place your baby on their back, on a firm and flat surface, in a bare sleep space, in your room. Keep the temperature comfortable, dress them appropriately, and offer a pacifier if they’ll take one. These steps aren’t just for nighttime. They apply to every nap, at home and at a caregiver’s house. Most sleep-related infant deaths involve at least one known risk factor, which means most are preventable.