Crossing the Midline in Children: What It Means, Why It Matters and When to Seek Occupational Therapy
Have you noticed your child switching hands halfway through colouring, turning their whole body to reach something, or finding activities like skipping, dressing or sport tricky?
You may have heard an Occupational Therapist talk about "crossing the midline". But what does that actually mean, and when is it something to be concerned about?
Let's take a closer look.
Key takeaways:
The midline is an imaginary line dividing the left and right sides of the body.
Crossing the midline means moving a body part into the space on the opposite side of the body.
Crossing the midline develops during early childhood, with more consistent use generally emerging around 4-5 years, however, individual development varies.
It is related to bilateral coordination, body awareness, postural control and motor planning, but these are not exactly the same skill.
Occasional hand switching is not automatically a problem. What matters most is the child's overall pattern, development and whether difficulties are affecting everyday activities.
Play-based activities can provide opportunities to practise crossing the midline, but they do not need to become a formal "occupational therapy program".
What is crossing the midline?
Imagine an invisible line running from the top of your head, through the centre of your body and towards the space between your feet. This is your body's midline.
Crossing the midline happens when a body part moves into the space on the opposite side.
For example, a child using their right hand to reach for a toy on their left side is crossing the midline.
We use this skill all the time. Reaching across a table, putting on a seatbelt, getting dressed, drawing across a page and rotating your body during sport can all involve crossing the midline.
It isn't just about the hands. The arms, legs, feet and trunk can all move across the body's midline.
When should children be able to cross the midline?
Crossing the midline develops gradually during early childhood as children develop bilateral coordination, motor planning, body awareness and postural control.
By around 4-5 years of age, children generally begin to demonstrate more consistent, spontaneous use of the skill during everyday activities. However, there is considerable individual variation, and occasional hand switching or avoiding a movement does not automatically indicate a developmental difficulty.
Rather than looking at a child's fifth birthday as a strict deadline, it's more useful to consider whether they are increasingly able to use both sides of their body together and naturally reach across their body during play and everyday tasks.
If difficulties are persistent beyond the early school years, particularly when they are affecting handwriting, dressing, self-care, sport or other activities, an OT assessment may be helpful.
What happens in the body and brain?
Crossing the midline is more complex than simply "moving a hand across".
Movement is coordinated by networks throughout the brain and body. Broadly, the left side of the brain primarily controls movement on the right side of the body, while the right side primarily controls the left. The two sides of the brain also communicate with one another through structures including the corpus callosum.
Successful movement across the body can therefore involve coordination between both sides of the body, as well as visual information, proprioception, balance, postural control, motor planning and attention.
This is why an Occupational Therapist looks at the whole movement pattern rather than assuming that a child simply has a "midline problem".
What's the difference between crossing the midline and bilateral coordination?
These terms are related, but they are not interchangeable.
Crossing the midline means moving a body part across the centre of the body.
Bilateral coordination means using both sides of the body together.
For example, cutting with scissors involves one hand cutting while the other stabilises the paper. Crawling and riding a bike also require coordinated use of both sides of the body.
Some bilateral activities involve midline crossing, while others do not.
Why might a child avoid crossing their midline?
A child might avoid crossing the midline because the movement is physically difficult, inefficient, unfamiliar, uncomfortable or simply not the strategy they have developed.
Possible contributing factors:
Postural control and core stability
Reaching across the body can be harder if a child has difficulty keeping their trunk stable.
Strength and endurance
A child may be able to cross the midline but become tired during repeated or sustained activities.
Body awareness
Proprioceptive information helps us understand where our body is in space.
Motor planning
Organising a new or complex movement can be challenging for some children.
Visual factors
Vision helps us understand where objects are in relation to our body.
Sensory processing
Differences in how a child responds to movement and body-based sensory information may affect how they organise movement.
Neurological or physical conditions
Conditions affecting movement, strength, coordination or vision can also contribute.
The important question is: "Why is this child avoiding the movement?"
Rather than treating every midline pattern in the same way, an Occupational Therapist considers what may be contributing to the difficulty.
What does difficulty crossing the midline look like?
One behaviour on its own does not necessarily indicate a problem. Look for consistent patterns that occur during everyday activities.
Hands and fine motor skills
You may notice:
Switching hands while colouring, drawing or writing
Using the left hand for objects on the left and the right hand for objects on the right
Moving or rotating the paper so the writing hand doesn't need to travel across the page
Becoming increasingly fatigued or frustrated during fine motor activities
Whole-body movement
You may notice:
Rotating the whole body instead of reaching across
Hesitating or appearing clumsy during movements that require the arms or legs to cross over
Difficulty with activities such as crawling, skipping, marching, throwing, catching or sport
Difficulty coordinating movements involving both sides of the body
Self-care
You may notice:
Difficulty reaching across the body when dressing
Difficulty with some aspects of brushing teeth or managing clothing
Difficulty with movements such as putting on a seatbelt or reaching behind the body
Visual skills
Some children may have difficulty scanning across a page or moving their eyes efficiently between visual targets.
However, visual difficulties should not automatically be labelled as a "midline crossing problem". If a child has headaches, eye strain, double vision, blurred vision or consistently loses their place when reading, an eye assessment may be appropriate.
Is switching hands always a red flag?
No.
Young children can have variable hand preferences, particularly while learning new skills. Hand preference develops over time, and there is considerable individual variation.
The more useful question is whether hand switching is interfering with what your child is trying to do.
For example, occasional switching while colouring is very different from a school-aged child who consistently switches hands during writing because neither hand can comfortably work across the page.
Why is crossing the midline important?
Efficient movement across both sides of the body can support many everyday activities, including handwriting, drawing, cutting, dressing, brushing teeth, sport, playground activities and household tasks.
It is one part of the broader motor skills needed for participation.
However, crossing the midline is not a magic prerequisite for learning to read or write. Reading and handwriting are complex skills involving many different factors, including language, visual-motor skills, fine motor control, postural stability, attention and practice.
What can you do at home?
If your child is otherwise developing well and you have simply noticed that they don't always cross their midline, you can provide opportunities through normal play.
Try:
Painting a large surface with big side-to-side movements
Washing windows or the car
Drawing large circles, zigzags or figure eights
Playing with scarves or ribbons to music
Throwing and catching soft balls or rolled-up socks
Kicking a ball
Playing Simon Says, Twister or movement games
Marching while touching the opposite knee
Reaching across the body to collect toys or objects during play
Threading, cutting, building and other activities that use both hands
The goal isn't to constantly tell your child to "cross your midline".
It is to create meaningful activities where reaching, rotating and coordinating both sides of the body happens naturally.
When should you seek an Occupational Therapy assessment?
You don't need an Occupational Therapy assessment every time your child switches hands or avoids one movement.
It may be reasonable to try playful activities at home when the behaviour is occasional, your child is otherwise developing well, there is no pain or significant coordination concern, and it isn't interfering with everyday activities.
An Occupational Therapy assessment may be useful when difficulties are persistent and affecting your child's:
Handwriting or fine motor skills
Dressing or self-care
Play or sport
Coordination
School participation
Independence
Confidence or willingness to participate
An OT can look at the movement in context and consider whether the difficulty is related to postural control, strength, motor planning, coordination, vision, sensory processing, fatigue or another factor.
If the difficulty appears suddenly, particularly alongside new weakness, balance problems, changes in vision, speech or other neurological symptoms, seek appropriate medical assessment rather than treating it as a developmental midline issue.
What does an Occupational Therapist assess?
There isn't one single test that tells us whether a child "has a midline-crossing disorder".
Depending on the referral question, an Occupational Therapist may observe:
Hand and foot preference
Bilateral coordination
Strength and endurance
Postural control
Motor planning
Body awareness
Visual-motor skills
How the child moves during real activities
How movement changes with fatigue, complexity or different environments
Standardised assessments such as the Movement Assessment Battery for Children or Beery VMI may be appropriate for some children, alongside clinical observation and functional assessment.
The most important question remains: How is this affecting the child's everyday life?
How can Occupational Therapy help with crossing the midline?
Occupational Therapy intervention depends on why the child is having difficulty.
Therapy may include:
Play-based motor activities
Bilateral coordination
Motor planning
Postural control
Fine motor skills
Visual-motor activities
Self-care practice
Environmental modifications
Strategies for home and school
The focus should be on the child's functional goals rather than simply making them perform a particular movement.
For example, if a child is struggling with handwriting, an Occupational Therapist may consider hand preference, pencil skills, posture, endurance, paper position and motor planning - not just whether the child can reach across their body.
I take a functional approach to children's motor skills. Rather than looking at one movement in isolation, we consider what your child is trying to do, what is getting in the way and why.
If you're concerned about your child's coordination, fine motor skills, self-care or participation, feel free to get in touch here:
Frequently Asked Questions
Does crossing the midline affect handwriting?
It can be one factor, but handwriting is much more complex than midline crossing alone.
Should I make my child use one hand?
Not necessarily. Hand preference develops over time. Rather than forcing a hand, it is generally more useful to observe natural preferences and seek advice if persistent switching is affecting function.
Can I practise crossing the midline at home?
Yes. Fun, age-appropriate activities involving reaching, rotating, throwing, catching, drawing, painting and whole-body movement can provide opportunities to practise these skills.
Does poor midline-crossing cause dyslexia?
No. Dyslexia should not be explained as being caused by poor midline crossing or a lack of "brain integration".
When should I see an OT?
Consider an OT assessment when difficulties are persistent and are affecting everyday activities such as handwriting, dressing, self-care, play, sport or school participation.
At what age should a child be able to cross the midline?
Most children develop increasingly consistent and spontaneous midline crossing during the preschool years, with more established use around 4-5 years. However, there is individual variation, so the overall pattern of movement and its impact on everyday activities is more important than a strict age cut-off.
Further Reading and Resources
Journal articles
Jacobs, J., Heymann, R., & Greeff, J. J. (2021). A telehealth system incorporating a serious game intervention to aid occupational therapists in identifying and treating children with difficulty crossing the body's midline: Key informant interviews among occupational therapists. JMIR Serious Games, 9(4), e27761.
Cermak, S. A., Quintero, E. J., & Cohen, P. M. (1980). Developmental age trends in crossing the body midline in normal children. American Journal of Occupational Therapy, 34(5), 313–319.
Hill, E. L., & Khanem, F. (2009). The development of hand preference in children: The effect of task demands and links with manual dexterity. Brain and Cognition, 71(2), 99–107.
Marion, S. D., Kilian, S. C., Naramor, T. L., & Brown, W. S. (2003). Normal development of bimanual coordination: Visuomotor and interhemispheric contributions. Developmental Neuropsychology, 23(3), 345–360.
Smits-Engelsman, B. C. M., Bloem-van der Wel, H. E., & Duysens, J. (2006). Children with developmental coordination disorder respond similarly to age-matched controls in both speed and accuracy if goal-directed movements are made across the midline. Child: Care, Health and Development, 32(6), 703–710.
Disclaimer
This article is intended as general information only and does not replace individual medical, therapeutic, educational or professional advice. Children develop at different rates, and a single behaviour does not necessarily indicate a developmental difficulty. If you have concerns about your child's movement, vision, coordination, development or participation, speak with an appropriately qualified professional.
