Infant Development in Prone

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Top Contributors - Stacy Schiurring and Jess Bell  

Introduction

Many families feel insecure and unsure about placing their infant in the prone position.  These feelings can stem from fear and confusion about the benefits of wakeful prone tummy time. It is important for rehabilitation professionals to understand the benefits and clinical reasoning behind supervised wakeful prone positioning on the physical, cognitive, and social development of typically-developing infants.

This article will overview the development in prone of typically-developing infants from birth to crawling.

Birth to Three Months

Phase indicator: when infants are placed prone they learn to lift their heads in a sustained manner.

Table 1.

Phase	Head	Spine	Upper Extremities	Lower Extremities	Special Notes
Newborn	Head kept turned to one side The infant is able to lift the head briefly and turn it to one side to free the airway	Full flexion of the hips in prone lying is associated with a posterior tilt of the lumbar spine	The upper limbs are held close to the torso with the shoulders in adduction and the elbows in flexion	Hips and knees flexed	Newborn position is influenced by the limited in utero space in the final weeks before birth, which create the “physiological contractures of the newborn” The body weight is distributed across the head, chest, and lower limbs
One to two months	Able to lift head up and off the support surface for increasing periods of time	Increasing strength and endurance of cervical and thoracic extensor muscle activity to lift and hold up head	Ability to lift head and shoulders up off the support surface allows infant to push up and support self on hands These actions allow the infant to roll back onto their back	Engages in active vigorous kicking: alternating unilateral and bilateral hip/knee flexion and extension Hip and knee flexion is associated with hip abduction. Hip extension is associated with hip adduction Active kicking contributes to stretching out flexed newborn position	Infants begin to discover how to roll themselves onto their backs
Two to Three months	Improved ability to lift their head and extend their thoracic spine This improving strength is also associated with taking some weight through their hands	Extension of the cervical and thoracic spine is associated with increasing extension and adduction of their hips		Continues to increase hip and knee extension Developmental feature: hip extension with adduction contributes to the increasing range of movement of the hips This phase marks the beginning of uncoupling of combined hip and knee flexion, and ability to dissociate movements of the two joints

Special Topic: Back-to-Sleep Campaign

While the developmental benefits of prone positioning is widely supported by research, prone positioning is not recommended during sleep.  

Sudden Infant Death Syndrome (SIDS) is defined as the “sudden death on an infant under one year of age which remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and review of the clinical history.”  Research has shown a dramatic decrease in the incidence of SIDS worldwide with the introduction of the Back-to-Sleep campaign.

One of the hallmark recommendations of The American Academy of Pediatrics’s (AAP) Back-to-Sleep campaign recommends infants be placed in a supine position for every sleep by every caregiver until the child reaches 1 year of age to reduce the risk of sleep-related death.  To learn more abou the AAP’s other recommendations please read this article.

Three to Seven Months

Phase indicator: When infants are placed in prone, they are able to take some weight through their hands and upper extremities to reach forward and play with toys.  

• Starting around four months, infants begin to find different ways to roll from supine to prone.
• During the four to six month period the infant will become more mobile in the prone position.  

Phase	Head	Spine	Upper Extremities	Lower Extremities	Special Notes
Three to Six Months	Continues to improve in the ability to lift head higher and for longer periods of time to explore environment	Lumbar extension develops	Infant is able to position upper extremities ahead of the shoulders to increase upper body and head lift	Lumbar extension is associated with hip extension and adduction, this brings the thighs in line with the pelvis	Environmental exploration is associated with changes in alignment, weight distribution, and trunk stability The infant explores different ways to use their limbs for support and increase mobility in prone such as the prone pivot
Six to Seven Months	Infants learn a range of overlapping abilities that reflect the increasing ability to lift the head, trunk, and lower limbs up off the support surface and also allows them to move about on the support surface. Skills include: Prone Pivot Prop sidelying/sitting Creeping Crawling Prone kneeling

• Prone Pivot:  infants gain more control over lateral weight shift over the upper limbs, they start to pivot in place as they reach for toys that are out of reach
• Prop sidelying/sitting:  the infant takes weight on one shoulder, forearm, and one lower limb. This position requires good weight-bearing shoulder stability, and the ability to right the head to one side, side flex the trunk, and dissociate the lower limbs with one hip is more extension or more flexion than the other.
• Creeping (commando crawling, belly crawling): Infants will often adopt an asymmetrical commando crawl pattern, pulling forward with one hand and pushing back with the other.
• Crawling:
  • Immature reciprocal crawling. When infants first learn to crawl, they do so with hips and shoulders abducted and the lumbar spine in lordosis.
  • Mature reciprocal crawling. The knees are aligned below the hips in neutral rotation, and the elbows are aligned below the shoulders. The lumbar spine is flat.
• Prone kneeling:
  • Reaching in prone kneeling. As infants’ balance in prone kneeling improves they start to reach for toys. To do this, the infant needs to rotate the shoulder girdle back away from the reaching hand. To make the position more stable the infant may shift the pelvis backwards over their knees.
  • Prone kneeling to sitting. Once infants can balance standing on their hands and knees, they will often transition into a half-sitting position propping on one hand.

Clinical Pearls: Hands-and-Knees Crawling

Hands-and-knees crawling is not always included as a developmental milestone because of the wide age of achievement found in the literature and the fact that many infants do not crawl on hands and knees before pulling up into standing.    Hands-and-knees crawling allow infants to explore different surfaces that challenge their balance and ability to figure out how to cross barriers and go up and down steps and slopes and soft surfaces.

• Infants can display multiple crawling patterns on route to walking
• Development of hands-and-knees crawling does not adhere to a strict progression of discrete stages, e.g. belly crawling to hands-and-knees crawling to walking
• The amount of time spent in earlier forms of crawling predicts the speed and efficiency of later more advanced forms of crawling
• Infants who had formerly belly crawled were more proficient at hands-and-knees crawling than infants who had skipped belly crawling

Many paediatric therapists contend that crawling is crucial for development and infants who do not crawl are at risk for developmental issues in later childhood. Presently there is no evidence to support this claim.  Further research is needed to make associations between short- and long-term motor, sensory, and cognitive benefits of crawling.  Rehabilitation professionals should be wary and mindful of where parents are getting their information about infant milestones and provide appropriate and evidence based information.

Seven to Twelve Months

Phase indicator: infants learn to creep and crawl as they acquire the needed strength, flexibility, coordination, and postural control to achieve this remarkable progress.  

ADD IMAGES from Video One with captions to give insight

Tummy Time

As discussed above, the AAP’s Back-to-Sleep campaign made a huge positive impact on the incidence of SIDS worldwide.  However, while the while the number of cases of SIDS decreased, infants placed in supine during sleep were found to have slower achievements of the motor milestones and an increase in head shape abnormalities. Focused and supervised prone positioning during waking hours can be used to counteract these effects.

Tummy time is defined as “awake prone positioning on the floor that is encouraged and supervised by an adult” and is recommended for infants less than six months of age.  It should be performed on a firm surface for at least 30 minutes a day.  This time cane be spread out in shorter bouts over the day to the infant’s comfort and tolerance. 

A 2020 study by Hewitt and colleagues reviewed the  existing evidence regarding the association of tummy time with a broad and specific range of infant health outcomes.

Sixteen articles representing 4237 participants from 8 countries were included. Most studies were observational in design and lacked the robustness of a randomized controlled trial. High selection and performance bias were also present.

The review findings indicated that tummy time was positively associated with gross motor and total development, a reduction in the BMI-z score, prevention of brachycephaly, and the ability to move while prone, supine, crawling, and rolling. An indeterminate association was found for social and cognitive domains, plagiocephaly, walking, standing, and sitting. No association was found for fine motor development and communication.

ADD IMAGES FOR ALTERNATIVE POSITIONS TO TUMMY TIME with caption stating

“Alternative tummy time positions for very young infants who do not tolerate being prone on a flat surface.”

Resources

Clinical Resources:

• Canadian 24-Hour Movement Guidelines for the Early Years
• Centers for Disease Control and Prevention Developmental Milestones
• World Health Organization Physical Activity Guidelines

Clinical Tests and Measures:

• Alberta Infant Motor Scale and related Physiopedia Page
• Evidence-Informed Milestones for Developmental Surveillance Tools
• Infant Motor Profile (app and link to purchase textbook)

Optional Additional Reading:

• Carson V, Zhang Z, Predy M, Pritchard L, Hesketh KD. Longitudinal associations between infant movement behaviours and development. International Journal of Behavioral Nutrition and Physical Activity. 2022 Dec;19(1):1-5.
• Jullien S. Sudden infant death syndrome prevention. BMC pediatrics. 2021 Sep;21(1):1-9.
• Kretch KS, Willett SL, Hsu LY, Sargent BA, Harbourne RT, Dusing SC. “Learn the Signs. Act Early.”: Updates and Implications for Physical Therapists. Pediatric Physical Therapy. 2022 Oct 1;34(4):440-8.