Back to Sleep & Infant Development | From a Pediatric OT & Mom of 2

Have you ever considered that your infant’s sleeping position has more of an impact on their development than you realize?

Infant development is a constantly evolving subject, as are many, due to the increase in consumerism, changes in world views, and new research studies to improve the health and safety of infants.

The Safe to Sleep initiative, formerly known of the Back to Sleep campaign, is exactly that — an initiative that encourages safe sleeping positions for infants to reduce the risk of Sudden Infant Death Syndrome (or SIDS).

The Safe to Sleep initiative was formed in 1992 by the American Academy of Pediatrics (AAP) and a healthcare coalition was founded to raise awareness, and encourage back sleeping in infants.

So why is back to sleep important?

The Safe to Sleep initiative was formed to minimize the risk of SIDS among infants, which is the leading cause of death in 1 month to 1 year old children. This initiative has been largely successful, in which the incidence of SIDS has been lowered by 60 percent after the AAP encouraged parents to place babies on their back to sleep. Post this initiative and suggestion, parents can now sleep deeply knowing their baby is safe. I, myself, am a firm believer in back to sleep as a safe sleeping position for infants. I know when placing my baby down on his back to sleep, he is safe because the airway is free.

So how did babies sleep prior to this initiative?

In the mid-1990s, it was very common for babies to be placed on their belly or side to sleep and also placed in a room far away from the parents. This sleeping position and change in location (away from the parent’s room) was to encourage uninterrupted sleep and “self soothing” as a means to foster independence among infants. This belly, or side, sleeping position significantly increased the risk of SIDS, therefore leading to the Safe to Sleep initiative. Read more about the history of infant sleeping patterns here. The Safe to Sleep initiative significantly reduced the risk of SIDS after parents began to place their infant on their back to sleep in order to prevent airway obstruction and suffocation.

But, just as infant sleeping positions and patterns have changed… so has infant development.

I had a difficult time locating research studies on how sleeping POSITION affects infant development, but I have my theories.

So let’s explore how these two things may be related.

First, let’s examine the position of a baby when sleeping on their stomach.

When a baby is placed on their stomach, the infant has their head turned to one side and, usually, place their arms out to the side of their body.

They may move around throughout the sleep cycle — repositioning themselves occasionally, but they will usually return to turning their head one direction or the other. The soft head of the baby is not touching the surface while sleeping — only the side of the face.

Now, what about back to sleep?

When lying on their back, the infant may turn their head to one side or the other, but the head may also stay at midline or to one preferred direction. In this back lying position, the force of the body weight is being distributed through the head and the whole back of the body as well. This is an important note because the infant’s head is very soft and this force applied through the soft areas of the head can cause shifts in mass, which leads to plagiocephaly and/or brachycephaly, or also known as, “flat head.”

So, what are the differences and why does this matter?

When a baby is placed on their belly, their head is turned one direction and their arms are often up, which offers a prolonged stretch of the head and shoulders as baby sleeps.

When a baby is on their back, this prolonged stretch is not completed and the baby is free to stay in their desired position as long as they wish. This continuous stretching of the body is not present during back sleep, which may affect the movement and development of the infant.

This absence of prolonged stretching can lead to tightness in the neck, which may contribute to side preferences and/or torticollis. In addition, this absence of a prolonged upper body stretch may lead to tightness in shoulders which may lead to delays in tummy time tolerance and rolling to name a couple.

When taking the prolonged stretching into consideration, it is imperative that we stretch our baby’s neck and body in all directions often, from day one, in the event that they are placed on their backs to sleep. This encourages flexibility, minimizes side preferences and encourages movement in all directions to prevent head flattening and encourage milestone development.

Let’s talk about the neck stretching a little more…

The head and neck are SO important in infants. Head control is the first thing to develop in infancy as far as milestones go. Flexibility is a precursor to strength, so neck flexibility (AKA range or movement) is very important. Like we discussed above, babies who sleep on their back may not have this flexibility due to the absence of the prolonged stretch. They may become stiff from sleeping in one position all the time, similarly to that of adults. We really have to prioritize stretching our baby’s neck in ALL planes from day one, just as we prioritize other things like tummy time and play development. If there is neck flexibility, then the baby will have a good foundation to develop strength which is crucial to head control. This head control leads all other motor development, for example rolling, sitting up, and more complex skills later in infancy.

This range limitation also can affect head shape. If a baby has a preference to a side, or prefers to position to head straight, this can cause stiffness in the neck which leads to head shape issues. This can lead to flattening on one side of the head (plagiocephaly) or flatness on the back of the head (brachycephaly). This wasn’t as much of an issue prior to the Safe to Sleep initiative because babies a) usually slept on their belly so there wasn’t sustained pressure through the head and b) usually had a sustained stretch of the neck while on their bellies.

Now, the prevalence of plagiocephaly, or flat head syndrome, has increased from 1 in 400 infants to 1 in 10 since 1992. This increase is related to the encouragement that back to sleep is the safest position for infants to sleep.

This head shape issue, or flat head syndrome prevalence, caused by the sleeping position, leads parents to place their babies in sitting and other positions sooner to get the pressure off the back of the head. This, in my professional opinion, affects the overall motor development progression of babies.

In addition, this sleeping position also makes belly-down play less tolerable because an infant has not spent a large amount of time on their belly. This limited time spent in this position, leads them to being uncomfortable in this position compared to a child that sleeps on their belly. This relates to the concept of desensitization in position due to lack of exposure. Baby hasn’t been on their tummy often, so they do not tolerant being placed in tummy time for long periods of time.

So, let’s dig more into the topic of milestone development considerations…

When a baby sleeps on their back, they are more comfortable on their back during daytime wake windows. This makes sense because they have spent large amounts of time on their back, which makes them enjoy the position.

So, present babies may not be as keen on tummy time, compared to previous generations, due to the absence of sleeping on their bellies. Babies may not tolerate tummy time as much and parents feel the need to start a clock when babies are placed on their bellies to encourage increased amounts of “tummy time.”

This difficulty with tummy time often leads to parents searching the web and socials to discover creative tummy time hacks and tips.

This lack of tummy time tolerance may lead to slower development in rolling belly to back skills due to decreased exposure to positions and possible limits of time spent problem solving in tummy time. Think about it, if a baby sleeps on their belly, then they are more willing to tolerate the position. This leads parents to allow more frustration among the baby which leads to problem solving and in turn, possibly rolling.

Let’s talk other milestones too!

Crawling is also initiated, typically, from a belly down position. This lack of tummy time exposure may affect an infant’s crawling development because they lack tolerance and willingness in this belly down position.

The CDC has deemed crawling as an optional milestone among infants (see crawling article here for more info) and the change is very timely with the push for Safe to Sleep sleeping position.

Remember, these are my theories, but from my personal and professional experience, all of this makes sense.

With this sleeping position comes other considerations as well in regards to milestones.

In my experience, we can consider the development of sitting and rolling skills as happening very closely together. Much different than before when belly to back rolling was charted to occur well before an infant could sit.

Current milestones state the following:

• Belly to back rolling by 4 months

• Back to belly rolling at 6 months

• Sitting well & crawling at 9 months.

These are based on this article by The Division of Developmental Pediatrics.

In my experience, milestones fall a little outside of these ranges and may be:

• Belly to back (from straight arms) & back to belly rolling around 5 to 8 months

• Sitting well around that same time (5 to 8 months)

• Crawling between 9 and 11 months

With this taken into consideration, when babies are placed on their backs to sleep, parents are more eager to place baby in an upright position to get the pressure off the back of the babies head. Which increases sitting skill development and reduces the opportunities for rolling development.

So to conclude…

I never realized how important sleeping position in infants was, and the considerations of these new sleeping position suggestions on infant development, until I had my own child.

I am a huge advocate for back to sleep because at the end of the day, we want to keep our babies SAFE.

But, I do believe the milestone charts should also reflect this change and parents do need to be aware of the consideration the sleeping position has on a) body tension and tightness b) head shape and c) infant development.

With these changes in sleep, it’s important to know how to encourage milestones and correct head shape among infants. I hope this was helpful!