If a baby is sleeping on the side, it is important to change their position. The safest sleeping position for a baby is on their back.

Putting a baby to sleep on their back greatly reduces the risk of sudden infant death syndrome (SIDS).

According to the National Institutes of Health (NIH), the rate of SIDS declined by 50% between 1994 and 1999. The rate of back sleeping more than doubled in the same period as a result of SIDS prevention campaigns promoting this position for babies.

Parents and caregivers may worry about what to do when a baby begins rolling onto their side or stomach. In most cases, there is no need to move the baby back, but people should continue putting a baby to sleep on their back, even after they can roll over.

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Sleeping on the side has associated risks in babies.

The American Academy of Pediatrics (AAP) advise that side sleeping is not safe for babies and offers no benefits.

The safest position for a baby to sleep is on their back. Some people mistakenly believe that side sleeping is safer for babies who vomit or have reflux, but this is untrue. Babies with reflux are no more likely to choke when they sleep on their backs.

Research does not offer specific guidance on when babies can safely transition to their side. For this reason, the AAP recommend putting babies to sleep on their backs for the first year of life.

While some medical providers previously advised placing newborns on their side to clear amniotic fluid, there is no evidence to support this recommendation.

The main risk of putting a baby to sleep on their side is that they will fall onto their stomach. When a baby is too young to support their head, this may mean that their face becomes stuck against the mattress, making it hard to breathe. Most babies can fully support and lift the head by the age of 4 months.

By about 3 or 4 months of age, many babies begin trying to roll over. Between 4 and 6 months, many can roll from their back to their stomach and then back again.

There is no need to roll a baby onto their back if they roll onto their side or stomach. A baby who can move into this position can turn out of it, as long as they are in a safe sleeping environment.

At about 6 months of age, many babies become more active sleepers, rolling throughout the night. However, it is still unsafe to put the baby to sleep on their side or stomach. If a baby rolls into this position, however, there is no need to wake or move them.

Some babies sleep better on their stomach or side. In fact, this is what can make these positions so dangerous. Babies enter deeper sleep for longer and may be more difficult to awaken. They may not wake up if they cannot breathe or need to move.

The simplest way to change a baby’s sleep position is to begin putting them to sleep on their back. Parents and caregivers may need to help the baby slowly adapt to this new position by nursing them to sleep before bed, gently rubbing their belly, singing to them while they fall asleep, or rocking them.

People should not use devices that hold a baby in position or prevent them from rolling. Infant sleep positioners actually increase the risk of SIDS because a baby may suffocate against the device. Restraining a baby’s movement may even prevent them from rolling out of an unsafe position.

Instead, it is best to focus on putting the baby to sleep on their back.

The following sleep safety tips can help keep a baby safe, even if they roll onto their side or stomach:

  • Sleep in the same room as the baby: A bassinet or crib next to the bed allows people to check on the baby easily. Ensure that pillows or other objects from the bed cannot fall into the baby’s sleep space.
  • Do not smoke: People who smoke should never smoke in the house or around the baby.
  • Do not use weighted blankets: Avoid using these or similar devices.
  • Prevent the baby from overheating: Do not use space heaters or keep the room too warm. Dress the baby in light clothing, rather than heavy fabrics or layers.
  • Use a swaddle: Make sure that it is tight at the chest but loose at the hips and knees. However, only use a swaddle before the baby starts rolling onto their side.
  • Stop swaddling once the baby can roll over: It is important to stop using a swaddle as soon as the baby starts moving on to their side.
  • Keep the crib empty: Do not put toys, blankets, pillows, or a bumper in the baby’s sleeping area.

Bed sharing

Some parents and caregivers choose to bed share with their infants. This practice remains controversial. In some cultures, it is a common custom, but in the United States, most pediatricians advise against it. The AAP emphasize that bed sharing before a baby is 4 months old presents the greatest risk.

Advocacy group La Leche League advise people who wish to bed share to follow these tips:

  • Do not smoke or allow the baby to sleep near a partner who smokes.
  • Do not bed share with a baby when intoxicated or otherwise impaired.
  • Bed share only if the baby breastfeeds.
  • Do not bed share if the baby was born prematurely.
  • Put the baby to sleep on their back.
  • Dress the baby in light clothing, not heavy layers.
  • Sleep only on a safe surface, which means not using a couch, chair, or bed that is excessively soft or covered in blankets and pillows.

The Academy of Breastfeeding Medicine encourage pediatricians to discuss bed sharing risk reduction strategies with new parents and caregivers. They also argue that bed sharing may improve sleep for the mother or caregiver and facilitate breastfeeding.

Sleep alarms

Some people use sleep alarms to keep their baby safe. There is no evidence that these alarms work, but they are new, so there might eventually be research supporting their use.

A sleep alarm is not a substitute for safe sleeping. These devices may be dangerous if they give people a false sense of safety or encourage them to use unsafe sleep practices.

Side sleeping in a baby increases the risk of SIDS, which is a leading cause of infant death.

While many factors can cause SIDS, a few simple modifications to a baby’s sleeping environment may help prevent it.

Parents and caregivers should consult a pediatrician for advice about helping a baby sleep better while still maintaining a safe sleep environment.