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Baby Sleeping on Side vs. Back

Medically Reviewed by Dr. Po-Chang Hsu, MD, MS
Which position is safer?

Side sleeping or back sleeping, which one is safer?

Babies really should come with instruction manuals, but unfortunately for us, they don’t. What they do come with is a lot of opinions!

Grandma might be telling you to put your baby on their stomach, and your friends are telling you to put them on their back. Meanwhile, your baby is insisting on sleeping on their side.

So which way is right? Does it even matter? Like all moms, we know you want what’s best for your baby. So let’s dig into the facts and the myths about your little one’s sleeping habits.

What Is SIDS?

One of the reasons it’s key to ensure your child sleeps on their back is to reduce the risk of Sudden Infant Death Syndrome, also known as SIDS.

SIDS is a blanket diagnosis given to children who die suddenly, with no other explanation, before the age of 1. SIDS is scary because, as the name indicates, it happens without warning. It’s also the leading cause of death in children between 1 month and 1 year of age (1).

Doctors have been trying for decades to decrease a baby’s chances of dying from SIDS — including providing recommendations for how our babies sleep.

In the 1970s and ’80s stomach sleeping was widely encouraged for new parents. It was thought this would help prevent babies from choking if they vomited in their sleep. Unfortunately, the result was that cot death, another term for SIDS, rose sharply during this time.

In 1992 the American Academy of Pediatrics officially began recommending children sleep on their backs to help reduce the risk of SIDS (2).

The recommendations seem to have worked because SIDS deaths have decreased from 130.1 cases per 100,000 live births in 1990 to 39.4 in 2015 (3).

This is the number one reason why your grandmother is wrong about sleep positions, and your baby should never sleep on their stomach. But what about side sleeping? Is it safe?

Unfortunately, the answer is no, and SIDS is not the only thing that can happen to a side sleeping baby.

What Can Side Sleeping Lead To?

Side sleeping might seem less dangerous than stomach sleeping, but it comes with its own set of problems.

Below are just a few things that can happen from side sleeping, and while some of them will not cause lasting danger to your baby, others can be harmful.

1. Plagiocephaly

Plagiocephaly is a flat spot that develops on your baby’s head, most often due to lying in one position too often (4). Baby’s skulls are very soft and pliable, and because of this, the pressure when they’re lying in a singular position can cause the skull to flatten.

While plagiocephaly is purely a cosmetic issue, it’s important to talk to your doctor right away if you notice it. That’s because it needs to be fixed while your baby’s skull is still pliable.

For mild cases, doctors will recommend repositioning or making sure you change your baby’s position often so that their skull has the opportunity to go back to normal and another flat spot doesn’t develop.

If the plagiocephaly is severe, your doctor might recommend helmet therapy to correct the shape of your baby’s head.

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2. Harlequin Color Change

Harlequin color change is a condition that occurs when the side the baby is laying on turns a different shade than the other side of their body.

This condition affects roughly 10 percent of newborns and is thankfully completely benign. Typically, their color will go back to normal within several minutes of being moved to a new position (5).

Doctors are not sure why this condition occurs, but they think it has something to do with the possible accumulation of red blood cells due to gravity.

3. Choking

Side sleeping can create a choking hazard for your baby because it can create torsion, or twisting, of the trachea which will make it difficult for your baby to breathe (6).

4. Rolling

When a baby sleeps on their side, it’s easy for them to roll to their stomach. If your baby is unable to roll from front to back, they’ll be stuck on their stomachs, and their risk of SIDS will rise.

5. Torticollis

Torticollis is the shortening of the neck muscle (sternocleidomastoid) that connects the head to the collarbone (clavicle). It can happen when the baby is not sleeping on the back but sleeps on the side or on the back with the head turned. Torticollis can cause abnormal muscle development and abnormal bone growth. Physical therapy or a recovery harness from the doctor can help resolve this problem (7).

Can Babies Ever Safely Side Sleep?

As a rule, you should always lay your baby down to sleep on their back until they are at least 12 months old. However, it’s okay to leave your baby on their tummy if they roll that way once they can consistently roll from tummy-to-back on their own.

Your doctor may — very rarely — recommend tummy or side sleeping if your baby suffers from a medical condition. However, if this is the case, they should also educate you on how to safely place your baby in their crib.

How To Stop Baby’s Side Sleeping

Now we know we definitely shouldn’t lay our newborns on their sides to sleep. But what if your newborn naturally moves to their side while sleeping?

Here are a few tips and tricks to help you keep your baby safely on their back.

1. Let Them Reach A Deep Sleep

If your baby wakes up when you are laying them down, they’re more likely to roll over into a position they find comfortable. Instead, cuddle your baby for 20 or so minutes until they fall into a deep sleep. The less likely they are to wake up, the less likely they are to change positions.

2. Swaddle Them

Swaddling provides your baby with comfort and security that mimics what they feel when you are holding them. When they feel secure and comfortable, they’ll be less likely to move positions to seek out that feeling.

It’s important to note that swaddling is a great way to comfort your baby — until they’re able to roll from back to front on their own.

At that point, it’s important to stop swaddling your baby, because if they roll to their bellies while swaddled, they may be unable to roll themselves back over. This will increase their risk of suffocation and SIDS.

3. Prop Them Up

Using pillows and rolled up blankets to hold one sleeping position can be great, but don’t put them under your baby! Instead, place them under your baby’s mattress to help prop them up and keep them comfortable without increasing their risk of SIDS (8).

A bare crib with no loose blankets or clothing is the safest for your baby.

4. Avoid Sleep Positioners or Wedges

Some parents may consider using sleep positioners for their baby who turns a lot. However, the United States Consumer Product Safety Commission (CPSC) and CDC have warned about the risks of suffocation with sleep positioners and wedges and advised against their usage.

5. Consistency Is Key

Babies thrive on schedules, and they like to know what’s going to happen next. If, after a few nights, your baby is still rolling over to their side, don’t give up. Keep consistently placing them on their backs — eventually, most babies will learn to stay that way.

When It’s All Said And Done

We understand that putting your baby to sleep can be a struggle, even without worrying over what position they take. But we also know children are the most precious things in life, and you want to protect them! Making sure they sleep on their backs is an essential part of doing that.

Headshot of Dr. Po-Chang Hsu, MD, MS

Medically Reviewed by

Dr. Po-Chang Hsu, MD, MS

Po-Chang Hsu, MD received his medical degree from Tufts University in Boston, Massachusetts. Dr. Hsu has interests in both pediatrics and neonatology, and he also loves writing, walking, and learning new languages.