Placing an infant on their side for sleep is strongly discouraged by all major pediatric organizations. The consensus among medical professionals is clear: the side position is not a safe alternative to sleeping on the back. Safe sleep guidance provides recommendations designed to reduce the risk of Sudden Infant Death Syndrome (SIDS) and other sleep-related infant deaths. Following these guidelines is one of the most effective steps caregivers can take to protect their baby by minimizing known hazards.
The Official Safe Sleep Recommendation
The current standard of care regarding infant sleeping position is known as “Back is Best,” and it advises that babies should be placed entirely on their back for all sleep times, including both naps and overnight sleep. Organizations like the American Academy of Pediatrics (AAP) issue these recommendations and advise consistently following them until a child’s first birthday. This guidance is a direct result of the “Back to Sleep” campaign, which began in the 1990s.
The introduction of this public health initiative led to a significant decline in the rate of sleep-related infant deaths. The campaign, now often referred to as “Safe to Sleep,” promotes the supine position as the best way to keep an infant’s airway open. This recommendation applies to every sleep period and every caregiver to ensure consistency, which is a major factor in reducing risk and has demonstrated a profound impact on infant safety.
Why Side Sleeping Increases Risk
The primary danger of the side position is its inherent instability. A baby placed on their side is significantly more likely to roll over onto their stomach (the prone position), which is the position most strongly associated with an increased risk of SIDS. This unintended roll can happen easily, especially for younger infants who have not yet developed the motor skills to reposition themselves. Due to this instability, the side position is not considered a safe alternative to back sleeping.
Once an infant is in the prone position, several physiological dangers can arise, including the risk of rebreathing exhaled air. When a baby sleeps face-down, particularly on a soft surface, they may breathe in air that is trapped around their face, which is high in carbon dioxide and low in oxygen. Stomach sleeping can also increase an infant’s body temperature, leading to overheating, which is another factor linked to a higher risk of SIDS. The prone position may also cause the baby’s airway to be less open compared to when they are on their back.
Managing the Rolling Milestone
The guidance for placing a baby to sleep changes slightly once they develop the motor skill to roll over independently. Rolling is a major developmental milestone that typically occurs between four and six months of age. When a baby can roll from their back to their stomach and back again, they have developed the strength and coordination to move out of an unsafe position.
It is still necessary to always start the baby on their back for every sleep. If a baby rolls onto their side or stomach on their own, they can generally be left in that position, as they have demonstrated the ability to choose and maintain it. Swaddling must be discontinued once a baby shows any signs of attempting to roll, ensuring the baby’s arms are free. Encouraging frequent “Tummy Time” while awake is beneficial, as it helps build the neck and shoulder strength necessary for repositioning.
Creating a Safe Sleep Environment
A safe sleep environment extends beyond just the baby’s position to include the entire sleep space. The surface should be firm, flat, and level, such as a mattress in a safety-approved crib or bassinet. A soft mattress, like one made of memory foam, can indent and increase the chance of rebreathing or suffocation if the baby moves into the prone position. The mattress should only be covered with a fitted sheet that is tight and secure.
The sleep area must be kept completely clear of any loose objects, as they can pose a suffocation or entrapment hazard. Items that must be excluded from the crib include:
- Blankets
- Pillows
- Bumper pads
- Stuffed toys
It is recommended to practice room-sharing, where the baby sleeps in the same room as the parents but on a separate sleep surface. This arrangement is advised for at least the first six months and can reduce the risk of SIDS by as much as 50 percent. Caregivers should also dress the baby in light sleepwear and keep the room at a comfortable temperature to prevent overheating.