About positional plagiocephaly, torticollis, and motor development

This article is part of a collection inside The Possums Sleep Program called Deeper Dive, which explores the more complex scientific, historical and social contexts in which families and their babies or toddlers live and sleep. You don't need to read Deeper Dive articles to be helped by The Possums Sleep Program.

What is positional plagiocephaly?

If your baby has flattening of or an unusual shape to the skull, please have this checked out by your family doctor.

Some babies have moulding of their skull as a result of the way they were carried in the womb, or the birth process. This moulding disappears around six weeks after the birth, by itself. Moulding of a baby's skull bones is different again to fluid collections on the head, which can also result from the birth process.

Positional plagiocephaly, which this article discusses, is different. It's a flattening of the back of a baby's skull, which develops in the weeks after the birth in an otherwise healthy child. It can be on one side or symmetrical across the back of the baby's head. Babies with positional plagiocephaly might also have

• Limited turning of their own head

• A preference for rotating their head and looking to the one side

• Asymmetry of their face and ears.

Positional plagiocephaly

• Doesn't affect the brain

• Peaks between 7-12 weeks of age

• Affects more than one fifth of healthy term babies

• Mostly resolves by about two years even without treatment. However, because we don't know which little ones will go on to develop worsening and permanent skull shape changes, assessment by your GP or paediatric physiotherapist is required

• Isn't caused by sleeping your baby on her back

• Is more likely if your baby was born prematurely

• Doesn't mean that your baby is at risk of developmental delays.

What causes positional plagiocephaly?

Researchers agree that positional plagiocephaly results from gravity acting on the same place on a baby's skull for too long a period of time. This happens in the first six or seven weeks after the birth, during a vulnerable period of rapid growth when baby's skull bones are still thinner and flexible, and her head large and heavy relative to her little body.

It's never the parents' fault when a flat spot develops, since there are many things outside our control in life, such as infant predisposition or the unique mouldability of any individual baby's skull.

But the effects of mechanical pressure on the one spot at the back of baby's head, without enough variation in the position of his head when he's on his back, can add up over those first weeks of life. This explains why the number of babies who developed positional plagiocephaly increased dramatically after 1992 when we started to sleep babies on their backs.

Sleeping your baby supine is an essential safety measure, which by itself doesn't cause positional plagiocephaly. Letting your baby sleep on her tummy won't help.

Positional plagiocephaly often occurs with a functional torticollis

Positional plagiocephaly is often associated with a functional torticollis of your baby's sternocleidomastoid muscles. Your health professionals might refer to this as a congenital muscular torticollis.

Functional torticollis occurs when the muscle fibres of one of your baby's sternocleidomastoid muscles are habitually more contracted than the other. As a result, your baby's head is slightly rotated to the more relaxed side with baby looking towards this side as a matter of preference. This rotational preference is likely to be accompanied by a slight tilting of the head toward the side of the tight sternocleidomastoid muscle, and towards your baby's shoulder on that tight side.

Please have your baby checked over by your GP if he holds his head and neck asymmetrically, because there are some kinds of torticollis which are due to damage or true congenital abnormality.

The torticollis we usually see with positional plagiocephaly is a result of changes in the way the neck muscles function, not due to structural damage or anatomic abnormality. A functional torticollis develops in the first days and weeks of life as your baby habituates a pattern of unbalanced or asymmetrical muscle contractions. In functional torticollis, your baby's neck and head can still be moved by you or your health professional in a normal range of motion.

Positional plagiocephaly and functional torticollis interact together

Functional torticollis and positional plagiocephaly interact together in the first weeks and months of life, though we hope to interrupt this!

It's not possible to say which comes first as a general rule. Both occur when a newborn spends long periods lying on her back without enough variation in the position of her little head. The less baby initiates rotational movements of her head and chin-to-chest tucks against gravity when lying on her back, the more likely it is that mechanical pressure will create a flat spot.

The worse the flat spot, the more of an obstacle there is to the baby initiating spontaneous head rotation movements and chin-to-chest tucks. Over time, the movement pattern on one side of his neck and body strengthens, whilst the other weakens.

In this way, patterns of movement imbalance are set up in a cascade which worsens both the skull flattening and the torticollis, at least for a time.

The things most likely to help prevent positional plagiocephaly are the same things which best protect motor development

Because positional plagiocephaly peaks from about seven weeks, we would apply baby care practices which might help prevent it from birth. It helps to think about the multiple factors which increase the amount of time mechanical pressure (from gravity) is applied to the same area on the back of your baby's head. It's about experimenting to see what feels workable in your own situation, not about perfection! You know best what is sensible and practical in life with your baby, in a way that no-one else can.

Your newborn will spend plenty of time sleeping (although not as much as you might think, given how variable baby sleep needs are). When you put her down asleep, she definitely needs to be on her back for safety. But when your newborn is awake, you might limit the amount of time she spends with the back of her head resting on the firm surface of

• Car capsules

• Cots

• Bouncers

• Mats on the floor.

This is definitely not a rule 'to never put baby down'! It's just knowing that when you have the energy for it, or when you have others available to help, giving the back of your baby's head a break from resting on a surface is a good thing.

Some parents protect the back of their newborn's head when she is awake and lying on her back by helping to keep the contractions of her sternocleidomastoid muscles in balance. (These strategies are often recommended once a flat spot has emerged.) You'd do this by

• Changing her position when she is lying down so she looks in variable directions

• Turning her head every now and then yourself

• Calling her and drawing her attention so she looks in a new direction.

Although parental effort goes into these exercises, they still only have a small impact on baby's movement patterns in a 24-hour period.

Often parents decide the easiest approach is to minimise the amount of time baby spends with the back of her head resting on a surface when she's awake

Other parents simply aim to minimise the amount of time their newborn spends with the back of her head resting on a surface. I think this is the easiest approach. When the baby is awake, you'd try to limit the time your baby spends in a

• Car capsule

• Bassinet or cot

• Pram

• Bouncer.

Families often find that their baby dials up if they put them down anyway (which is normal baby behaviour). So the days seem be easiest if they put their newborn in a carrier instead of struggling against the baby's biological drive to be up close. I explore how to use carriers easily from birth here, and how to use them safely here.

Why does positional plagiocephaly matter?

Families naturally worry about how the way a flat spot on the head and changes in the shape of baby's face looks. They certainly don't want the flattening to get worse, if they can help it, and would prefer to prevent it if they could. It's comforting to know that no matter what you do, positional plagiocephaly tends to resolve as the little one grows, or at least becomes much less obvious, anyway.

But there have also been concerns about possible links between positional plagiocephaly and developmental delay.

• Some studies have suggested that a small subset of babies with positional plagiocephaly show some signs of developmental delay (particularly in motor development) at two years of age. However, the most recent analysis of all existing evidence on this topic argues that the quality of the research is too weak for any conclusions to be drawn.

• Preschool children who had positional plagiocephaly as infants tend to have lower developmental scores, particularly in motor skills. Again, the long-term impacts aren't clear and may not be significant.

So the way I see it, positional plagiocephaly is generally not a big worry. But a flat spot on the back of your baby's head is something that says to us: "maybe this is a little one who could do with more sensory motor nourishment". There are ways of changing your days and nights to do this, without you having to make a big effort, discussed here.

In fact, the steps in the NDC bodywork approach to supporting your baby's sensory motor development usually make the days and nights with your baby easier and more enjoyable, rather than harder, believe it or not! You can find out about these here.

I explore more about the possible prevention of positional plagiocephaly from an evolutionary perspective here.

If your baby has developed a flat spot on the back of her skull, please discuss this with your GP, paediatric physiotherapist, or osteopath. It does seem that the earlier treatment is started, and the younger the baby is, the quicker flat spots resolve. The benefits of helmet therapy continue to be debated, and the need for helmet use in severe positional plagiocephaly is a decision to make in discussions with your baby's doctor, after proper assessment.

Recommended resources

What is sensory motor nourishment and why does it help with baby sleep?

Filling your baby's sensory tank

Why baby wearing makes life easier (not harder)

What your baby needs for best possible motor development

The holistic NDC or Possums 8-step approach to supporting baby's motor development

The NDC evolutionary perspective on positional plagiocephaly, motor development and sleep

Selected references

Charalambous L, Hadders-Algra M, Yamaski EN, Lampropoulou S. Comorbidities of deformational plagiocephaly in infancy: a scoping review. Acta Paediatrica. 2024;113:871-880.

Cho HG, Ryu JY, Lee JS. A study on the effectiveness of helmet therapy for cranial deformations according to cranial shape. Journal of Craniofacial Surgery. 2024:doi: 10.1097/SCS.0000000000010018.

De Bock F, Braun V, Renz-Polster H. Deformational plagiocephaly in normal infants: a systematic review of causes and hypotheses. Archives of Disease in Childhood. 2017;102:535-542.

Graham T, Gilbert N, Witthoff K. Significant factors influencing the effectiveness of cranial remolding othoses in infants with deformational plagiocephaly. Journal of Craniofacial Surgery. 2019;30(6):1710-1713.

Hillyar CR, Bishop N, Hibber A, Bell-Davies FJ, Ong J. Assessing the evidence for nonobstetric risk factors for deformational plagiocephaly: systematic review and meta-analysis. Interactive Journal of Medical Research. 2024;13:e55695 doi: 55610.52196/55695.

Martiniuk ALC, Vujovich-Dunn C, Park M, Yu W, Lucas BR. Plagiocephaly and developmental delay: a systematic review. Journal of Developmental and Behavioral Pediatrics. 2017;38(1):67-78.

Renz-Poster H, De Bock F. Deformational plagiocephaly: the case for an evolutionary mismatch. Evolution, Medicine, and Public Health. 2018:180-185.

Williams E, Galea M. Another look at 'tummy time' for primary plagiocephaly prevention and motor development. Infant Behavior and Development. 2023;71:101839.