The safest approach is to always place your newborn on their back for every sleep, on a firm, flat surface with nothing else in the crib. Side sleeping is not a safe alternative. Studies show that infants placed on their sides are roughly twice as likely to die from SIDS compared to those placed on their backs, largely because the side position is unstable and babies can easily roll from there onto their stomachs.
Why Side Sleeping Is Risky
The side position might look comfortable, but it’s the transitional posture most likely to end with a baby face-down. The AAP is clear: the side position is not considered a safe alternative to sleeping wholly on the back. Babies who are used to back sleeping but are then placed on their sides or stomachs face a significantly higher risk of SIDS than babies who always sleep on their backs.
The reason comes down to muscle control. Newborns lack the neck and core strength to lift or turn their heads reliably if they end up face-down. A baby who rolls from their side to their stomach on a sleep surface may not be able to clear their airway, and that’s when suffocation becomes a real danger.
Practical Ways to Keep Your Baby on Their Back
Most of what keeps a newborn from rolling onto their side involves setting up the sleep environment correctly, not adding products to the crib.
- Use a firm, flat mattress. A mattress that passes current safety standards fits snugly in the crib with no more than about 3 inches of gap at the corners. A firm surface gives your baby less opportunity to sink in and shift to one side. Soft or plush surfaces allow a baby’s weight to create a slope that encourages rolling.
- Keep the crib completely empty. No pillows, stuffed animals, bumpers, blankets, or rolled towels. Parents sometimes wedge blankets along a baby’s sides to keep them in place, but loose items in the crib are a suffocation hazard. The only thing on the mattress should be a fitted sheet.
- Swaddle correctly (while it’s still safe to do so). A proper swaddle with arms snug can help a very young newborn feel secure on their back and reduce the startle reflex that sometimes causes them to shift. The swaddle should be firm around the arms and chest but loose at the hips to allow healthy leg movement.
- Place your baby in the center of the crib. Putting them off to one side means they may press against the crib wall and use it as leverage to turn.
Do Not Use Sleep Positioners or Wedges
It’s tempting to buy a product specifically designed to hold your baby in place. Foam wedges, bolster-style positioners, and angled sleepers are marketed to parents for exactly this worry. But both the CPSC and the FDA have warned against all of them. Over a 13-year period, 12 infants between 1 and 4 months old died after suffocating in or against sleep positioners. Most of those babies suffocated after rolling from a side position to their stomachs while using the device.
The FDA has never cleared any infant sleep positioner to prevent SIDS. No scientific evidence supports their safety or effectiveness. The official position from both agencies is direct: using a positioner to hold an infant on their back or side for sleep is dangerous and unnecessary.
When to Stop Swaddling
Swaddling helps keep very young newborns settled on their backs, but it becomes a hazard the moment your baby starts showing signs of rolling. That typically happens around 2 to 4 months, though some babies show signs earlier. A swaddled baby who rolls onto their stomach has no way to use their arms to push up or reposition, which increases the risk of suffocation.
Watch for these signs that it’s time to transition out of the swaddle:
- Attempting to roll during sleep or when placed on a flat surface
- Regularly breaking free of the swaddle wrap
- Preferring arms out, fussing when wrapped, or seeming restless
- Signs of overheating, like sweating, flushed cheeks, damp hair, or rapid breathing
Once you see any of these, switch to a wearable sleep sack that leaves your baby’s arms free. This keeps them warm without restricting their ability to move if they roll.
What Happens When Your Baby Can Roll on Their Own
Before a baby can do a full roll, they typically start with a half-roll onto their side. This is a normal part of development and usually emerges around 3 to 4 months. Belly-to-back rolling tends to come first, around 4 to 6 months, followed by the harder skill of back-to-belly rolling shortly after.
The AAP’s updated 2022 guidelines address this directly: once your baby can roll both ways, from back to stomach and from stomach to back, you can let them stay in whatever position they choose. You should still place them on their back at the start of every sleep, but you don’t need to go in and flip them if they roll over on their own. The key is that your baby has demonstrated the strength and coordination to move freely in both directions.
Until that milestone, continue repositioning your baby onto their back if you find them on their side. This is especially important during the first few months when the startle reflex or a slightly uneven surface can cause an unintentional shift.
How Tummy Time Helps
Daily supervised tummy time while your baby is awake builds the neck, shoulder, and arm strength that eventually makes rolling safe. These are the same muscles a baby needs to lift their head and clear their airway if they end up face-down. Tummy time doesn’t prevent rolling during sleep, but it accelerates the development of the motor control your baby needs to protect themselves once rolling becomes inevitable.
Start with a few minutes at a time on a firm surface while you’re watching, and gradually increase as your baby tolerates it. Even short sessions several times a day add up. By the time your baby is strong enough to roll both ways confidently, you can worry less about sleep position, because their body will have the strength to handle it.