No, side sleeping is not considered safe for newborns. Babies should always be placed on their backs to sleep, and a newborn who shifts onto their side should be gently repositioned. The distinction that matters most is whether your baby is reflexively curling to one side (common in the first few weeks) or intentionally rolling over (a milestone that typically happens months later). Each situation calls for a different response.
Why Side Sleeping Raises the Risk
The Back to Sleep campaign in the 1990s led to a significant drop in sleep-related infant deaths after the American Academy of Pediatrics recommended that all babies be placed on their backs. The reason side sleeping is specifically discouraged: a baby on their side can easily roll onto their stomach, where the risk of suffocation increases. A pooled analysis of earlier studies found that side sleeping carries roughly twice the risk of SIDS compared to back sleeping.
A soft mattress makes this worse. When a baby ends up face-down on a surface that conforms to the shape of their head, it creates pockets around the nose and mouth that trap exhaled air. The baby breathes in carbon dioxide instead of fresh oxygen. A firm mattress, one that doesn’t indent under the weight of a baby’s head, reduces this danger considerably. This is why the AAP recommends a firm, flat surface with nothing but a fitted sheet.
The Newborn Curl Is Not Rolling
Many parents notice their newborn scrunching to one side shortly after being placed on their back. This is the newborn curl, a reflexive posture left over from months spent curled up in the womb. The baby’s muscles and joints are still adjusting to open space, so they instinctively tuck their knees and keep their arms close to the chest. It can look like they’re trying to roll, but it’s not intentional movement.
This reflex typically fades by around 3 months. It does not mean your baby is ready to roll, and it is not a reason to stop swaddling. True rolling is a deliberate, coordinated motion where the baby moves fully from back to side to stomach (or the reverse). Most babies figure out tummy-to-back rolling around 6 months, with back-to-tummy rolling following shortly after because it requires more strength and coordination.
What to Do When You Find Your Baby on Their Side
If your newborn shifts onto their side after being placed on their back, gently roll them back. At this age, they don’t have the muscle control to reposition themselves if they end up in a compromised position, so you need to intervene. You don’t need to stay awake watching them all night, but repositioning when you notice it is the right move.
Once your baby can roll independently in both directions, the guidance changes. At that point, if they roll onto their side or stomach on their own, you can leave them. A baby with the strength to roll themselves over generally has the neck and upper body control to lift their head and shift if their airway becomes blocked. The key rule stays the same: always place them on their back at the start of every sleep, even if you know they’ll flip themselves over within minutes.
Skip the Wedges and Positioners
It’s tempting to buy a product that promises to keep your baby on their back. Don’t. The FDA has issued direct warnings against infant sleep positioners, including wedge-shaped devices and bolster-style products designed to hold a baby in one position. These products have been linked to suffocation deaths. Babies can roll from a side position into the padding, scoot upward or downward and become trapped, or end up pressed against the bolster with their airway blocked.
No baby product currently on the market has been cleared or approved by the FDA to prevent SIDS. Any product making that claim is doing so without scientific evidence to support it.
When to Stop Swaddling
The newborn curl alone is not a sign that you need to ditch the swaddle. Since it’s a reflex rather than intentional movement, your baby isn’t at the stage where swaddling becomes dangerous. The moment your baby rolls fully onto their stomach at any age, however, swaddling needs to stop immediately. A swaddled baby who ends up face-down cannot use their arms to push up or reposition, which creates a serious suffocation risk.
Once your baby starts showing signs of intentional rolling, transition to a sleep sack with open arms. This keeps them warm without restricting the arm movement they need to stay safe if they flip over during the night.
Setting Up a Safe Sleep Space
The safest setup is straightforward: a firm, flat mattress with a single fitted sheet, inside a crib or bassinet, with nothing else in it. That means no pillows, blankets, quilts, stuffed animals, or bumper pads. A firm surface is defined as one that holds its shape under your baby’s weight rather than conforming around their head.
Your baby should sleep in their own space, not in your bed. Room-sharing (baby in a crib near your bed) is fine and even encouraged in the first several months, but bed-sharing introduces additional risks from soft adult bedding and the possibility of an adult rolling toward the baby.
Giving your baby plenty of supervised tummy time during the day helps them build the neck, shoulder, and core strength they’ll eventually need to roll safely and reposition themselves during sleep. It also helps them reach that rolling milestone sooner, which is ultimately what makes overnight position changes less concerning.