Interactions between positional plagiocephaly, motor development, and sleep: NDC evolutionary bodywork
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.
The Homo sapiens baby is most accurately understood as 'an exterogestate foetus' for the first nine months of life
The human baby is most accurately conceptualised as a 'foetus outside the womb' for the first nine or so months of life. The concept of the fourth trimester has value in communicating the baby's biological need for physical closeness, responsive care, frequent flexible breastfeeds and rich sensory nourishment in the first three or four months of life, but also inaccurately truncates our understanding of the baby's evolutionary and biological needs throughout the first year of life. Sometimes the concept of the fourth trimester has even been used to support a belief that after the fourth trimester, a baby is ready for implementation of sleep training strategies.
Here, I'm applying the theoretical frames of evolutionary biology and complexity science to the emerging research concerning positional plagiocephaly. These are the two theoretical frameworks I've used in the development of Neuroprotective Developmental Care (or the Possums programs), more generally.
In a 2017 systematic review, De Bock et al considered the theoretical frame of evolutionary biology as a way of making sense of positional plagiocephaly. In a comprehensive 2023 review, Williams & Galea put forward a hypothesis showing how the development of positional plagiocephaly and functional torticollis interact and co-evolve. Their proposals correspond with the clinical impression I've formed about this over many years of practice.
Like most research in infant development, motor development milestones have been described sequentially by researchers studying white babies in specific subcultures within Western societies, resulting in really quite extreme bias in developmental psychology.
In reality, infant motor development is highly variable, not necessarily sequential according to Western norms, and affected by cultural practices and values across the great diversity of human cultures in the global majority. Certain cultures select out and encourage aspects of movement that matter to them, within their own cultural constraints. For example, infants don't crawl in some cultures until after walking, with no negative impacts on motor development overall.
Positional plagiocephaly: how the NDC or the Possums evolutionary bodywork approach minimises mismatch between biology and culture
| Newborn's evolutionary expectation | Key elements which protect against positional plagiocephaly | Contemporary infant care practices which might predispose to positional plagiocephaly | NDC or the Possums programs |
|---|---|---|---|
| Social sleep | Bedsharing or 'breastsleeping' results in increased proportion of active sleep with higher muscle tone and more arousals (which don't necessarily require maternal assistance), during which baby repositions her head in the supine position. The woman also regularly repositions baby as she tends to warmth, safety, and breastfeeding from alternate sides of her body | Sleeps in same room as parents on own sleep surface, or in separate room with or without monitor. Solitary sleeping results in less active sleep and less infant-initiated repositioning of the head in the supine position; no parent-initiated repositioning of the head; baby may be wrapped or swaddled which further decreases amount of active sleep and infant-initiated repositioning of the head | Bedsharing supported in the context of education about risk minimisation and parent choice; wrapping or swaddling not promoted, but parent choice and wrapping safety emphasised |
| Baby transport occurs on adult bodies | Spontaneous general movements more likely to trigger sensory input (e.g. arm and hand movement through efferent neurons result in contact with parental body, eliciting tactile, pressure and warmth feedback through afferent neurons) and further baby-initiated movement in response; constant small changes of relationship to gravity as parent moves triggers constant micro-postural adjustments in relation to gravity; high levels of incidental social interaction with parent which elicit symmetrical or variable sternocleidomastoid flexion and extension through eye contact and following carer’s face | Transportation in pram, car capsule, also time spent lying awake in bouncer or rocker or cot increase mechanical pressure on back of head; limit sensory feedback from general movements; result in less incidental social interaction with parent which decreases opportunities for symmetrical sternocleidomastoid flexion and extension or variable head rotations | When possible and sensible, multiple adults transport baby in carrier device or hold baby in arms, because this dials baby down and makes life more manageable for parents |
| Multi-centric social interactions with highly physical focus | Baby motivated by innate drive to elicit interaction with loving others, which drives motor impetus for movement, which triggers sensory input as a result of the movement; to and fro communication with adult including eye contact results in multiple opportunities to flex/extend neck, rotate head | Interactions with single adult, highly verbal focus; primary carer spends long periods during day alone with baby, often with focus on sleep routines and getting baby down supine into cot to sleep, which decreases movements of flexor neck muscles and head rotation, and increases mechanical pressure on back of head | Focus on providing baby with rich and changing sensory experiences outside the house, which increases social interactions either incidentally or by other adults and children who care about the baby |
| Daytime breastfeeding | Repetitive suckling in prone position with cervical-to-sacral-spine alignment; constant opportunities to practice symmetrical flexion and extension of sternocleidomastoid muscles, and forward flexion of spine and trunk in prone position | Hyperextension of spine is common in ‘baby-led’ or ‘biological nurturing’ methods of fit and hold; lateral rotation of neck and spine common in standard approaches to fit and hold; cross-cradle hold interrupts flexion and extension of the neck against gravity; breastfeeding pillow use applies mechanical pressure to back of skull | Gestalt method of fit and hold emphasises spinal alignment and infant prone positioning with mother semi-reclined |
| Night-time breastfeeding | Repetitive suckling in side-lying position | Standard side-lying approaches often involve spinal misalignment, cervical spine rotation and lateral flexion, asymmetric sternocleidomastoid muscle use | Side-lying using the gestalt method fit and hold emphasises spinal alignment with repetitive opportunities to practice symmetrical or rotational uses of sternocleidomastoid muscles |
| Bottle feeding may be spaced out; may sometimes occur in propped up contexts with baby’s head against firm surface | Bottle feed using paced bottle feeding method, frequently and flexibly; baby held in arms, parent responsive to baby cues |
Acknowledgement
I acknowledge the traditional owners of the land upon which I've created The Possums Baby and Toddler Sleep Program here in south-east Queensland, the Yuggera and Turrbal peoples, whose babies and toddlers have been sleeping easily and soundly in the midst of their families, close to loving adults’ bodies, for anywhere up to 65,000 years.
Recommended resources
About positional plagiocephaly and motor development
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
Selected references
Amir D, McAuliffe K. Cross-cultural, developmental psychology: integrating approaches and key insights. Evolution and Human Behavior. 2020;41:430-444.
Craighero L. An embodied approach to fetal and newborn perceptual and sensorimotor development. Brain and Cognition. 2024;179:106184.
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.
Douglas PS. Pre-emptive intervention for Autism Spectrum Disorder: theoretical foundations and clinical translation. Frontiers in Integrative Neuroscience. 2019;13(66):doi.org/10.3389/fnint.2019.00066.
Franchak JM, Adolph KE. An update of the development of motor behavior. Wiley Interdisciplinary Reviews: Cognitive Science. 2024;15:e1682. doi: 1610.1002/wcs.1682.
Medonca B, Sargent B, Fetters L. Cross-cultural validity of standardized motor development screening and assessment tools: a systematic review. Developmental Medicine and Child Neurology. 2016;58:1213-1222.
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.
Renz-Polster H, Blair M, Ball H, Jenni OG, De Bock F. Death from failed protection? An evolutionary-developmental theory of Sudden Infant Death Syndrome. Human Nature. 2024:https://doi.org/10.1007/s12110-12024-09474-12116.
Wang Y. Cultural differences in infant motor development: a comparison of early locomotor experience: Simon Fraser University; 2022.
Williams E, Galea M. Another look at 'tummy time' for primary plagiocephaly prevention and motor development. Infant Behavior and Development. 2023;71:101839.