Key Development Concept: Crossing the Midline

Main Idea:

  • The midline is the vertical center axis of baby’s body

  • Play that stimulates and encourages baby to cross the midline at every stage of development is a building block for advanced motor skills, language, and so much more

  • Engaging in midline play is easy! We’ll show you how

The ‘midline’ of our bodies describes the invisible vertical axis that organizes our bodies symmetrically into two sides - left and right. Think of a vertical line that runs down the bridge of your nose and through your belly button.

As adults, we intuitively and naturally ‘cross’ this midline countless times a day to perform tasks. Our ability to cross the midline is so innate that we never think about it, but it is essential to our ability to be active in the world. Every time you do seemingly simple things like watching a moving car go by, tying your shoes, combing your hair, and so much more - you’re crossing the midline!

After birth, however, your baby must learn to establish their midline with time and practice as they build each and every day towards an integrated cognition that directs the fluid use of both sides of the body.

The Science

‘Crossing the midline’ is not only a physical task but a cognitive one too! Well before you’ll see evidence of your baby physically crossing the midline, their brain is hard at work setting the foundation for crossing the midline via the corpus callosum! The ‘corpus callosum’ is a bundle of over 200 million nerve fibers that connects the left and right hemispheres. Think of it like the superhighway of information between both sides of the brain.

Fun Fact: The corpus callosum tends to form around the 20th week of gestation and will continue to grow in density until about age 12. As your child develops, this pathway grows in complexity and speed - like going from a walking path to an 8 lane highway!

Think of ‘crossing the midline’ as a dialogue between the left brain (analytic, logical) and right brain (intuitive, creative) activity which are in turn responsible for the right and left sides of the body, respectively. 

As a result, we know that a fluid ability to center and operate on both sides of the midline relates to other physical and cognitive abilities in baby including:

  • Attention
  • Spatial orientation
  • Visual-motor skill
  • Coordination
  • Memory (especially spatial)
  • Planning (motor planning)
  • Increased confidence + reduced anxiety (As a result of centering)
  • Language Development
  • Reading
  • Writing

Dr. Stephen Cowan

“Learning to be ‘centered’ as a human starts from the very inception of life as we develop an awareness of our midline. The midline is a bridge between our ‘two halves’ - our arms, legs, eyes, ears, nostrils, and the two hemispheres of the brain. Both sides of the body and mind are in constant dialogue with each other, converging at our midline. As parents watching our babies develop their midline awareness, we must remind ourselves to find balance in our lives and ‘center’ ourselves in the midst of ongoing change. This is resilience.”

-Dr Stephen Cowan

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Establishing and Crossing the Midline: A Progression

Establishing a sense for the midline and later ‘crossing’ it begins sooner than you probably think as babies are able to cross the midline with their eyes, hands, and feet.

At every stage of development there are opportunities to promote a sense for the midline in increasingly sophisticated ways. 

Engaging in play that promotes midline awareness and opportunities to build strength as they work toward crossing the midline are powerful ways to support your child’s development.

Here’s how:

Establishing the Midline:

In the early days, providing as many opportunities as possible for skin-to-skin contact is key! In addition to skin-to-skin contact with you, remember to provide opportunities for baby to have contact with themselves. As touch sensors develop, this will help your baby establish body awareness.

The easiest ways to do this are during swaddling and massage which have a myriad of other benefits:

Activity: Swaddling

When swaddling, ensure that you organize baby’s arms so they are together with the opportunity to touch fingertips. This allows them to make contact with touch receptors on both sides of the body.

Activity: Nose to Toes Texture

Find two textures — a dry wipe and a wet wipe, for example — and trace a continuous line down each side of your baby’s body. Start at the top of the forehead, gently tracing your baby’s cheeks, then down toward their shoulders and abdomen. Criss-cross the textures as you trace down the legs. If you have time, repeat this motion with textures on the opposite sides.

A Note on Holding Baby:

If you notice that you have a tendency to hold baby on one side of your body, try holding them on the other side. This provides a variety of input to their vestibular system (balance and spatial awareness) and will encourage use of the neck in different positions as they are inclined to look towards their favorite thing - your face!

Activity: Bottoms Together

Simply bring the bottom of baby’s feet together flat against each other to provide another opportunity for contact with their own body. With their feet secured by your hands, you might find that this gives them a bit more stability in the top half of their body to experiment with movement.

Tracking Objects

Some of the earliest evidence of crossing the midline begins when baby starts to track objects from side to side - using all their senses! Baby can ‘track’ not only with their eyes but also with their sense of smell, touch, and hearing which gives you an opportunity to activate these senses.
Early in development you’ll notice that eye movements are tied to head movements, so as baby transitions their gaze from side to side they are also experimenting with shifts in weight and activating an early sense for the midline.

Activity: Flying Wipe

Pretend Our Wet Wipes are a bird flying in the air and track the bird slowly from one side of baby’s natural gaze to the other to attract their attention. Every few seconds, you can land the bird on a body part and name where it landed: "That little birdie landed on your tummy!" This activity encourages visual tracking across the midline.

Activity: Essential Oil Tracking

At an appropriate time, gently introduce to your child a fragrance (our essential oil roller balls are a great option) on one side of their body by holding it near their nose. Notice if the location of the fragrance attracts their head to move to one side. If so you’ve successfully encouraged them to activate motor control for crossing the midline! Try on the other side and see if you can get them to move gently from one side to another.

Discovering Hands + Feet

With more established neck control and spine strength, you’ll notice that baby now has the ability to bring both hands to center by grabbing an object. Next you’ll likely notice that as baby brings their feet up they might grab for their feet for the famous ‘Happy Baby’ yoga pose. As they discover their hands and feet they are growing their awareness of the laterality of their body and the connections between their entire body.

Activity: Grab the Opposite Foot

If baby is reaching for the foot on the same side of the body (ex: right hand reaches for right foot) encourage them to reach across the midline and grab and hold the opposite foot. You can gently connect their hand to their foot for them.

Activity: Bicycling Legs

With your baby lying down, take hold of both of legs and pedal them as if your little one is biking. Play music or sing while doing so, and pedal your baby’s legs to the rhythm of the beat.

Activity: Criss Cross

Do some gentle stretches with your baby as part of the morning or afternoon routine. With your baby in your lap, slowly stretch out their arms, up, then down, then in and out. Next, cross your baby's arms around the body (like a self hug). Do this first with the left arm over the right arm, and then switch, bringing the right arm over left. Try switching this up by doing stretches to the beat of music.

Tummy Time

Tummy time is an essential activity throughout early development and helps strengthen the entire chain of muscles in the neck, back and legs. Early in tummy time, baby will have their head facing one side and their arms at their sides until they are able to create the strength to prop themselves up on their elbows, allowing the head to rest neutrally at the midline. Building muscle tone and fluid motor coordination allows for greater midline opportunities as their range of possible movements expand.

Activity: Tummy Reach

Place your baby on their tummy and hand them a toy to play with — allow your baby to hold it, shake it, observe it. Then, gently take the toy from your baby and place it just out of reach. As they try to reach for it, offer encouragement and celebrate their efforts! 



Your baby may perform their first roll coming off of their stomach (during tummy time) and rolling to their back. It may be an accident at first as they are learning their body, but soon they will be excited to try again. Rolling opens the opportunity for the side-lying position which frees one side of the body to move more freely. You can encourage them to roll to one side by moving to their opposite side and calling for their attention or placing an object of interest just out of reach to encourage rolling.


Once baby has gained the core and pelvic strength to sit without using their hands, they will naturally begin to explore what they can reach around them. As their ability to stay upright increases, they will begin to explore rotating their trunk and extending their arms to explore the world around them.

Activity: Coin Bank

Using a coin bank, or even just a cardboard box with cutout slots, show your little one how to place “coins” in the bank; next, give your little one a try. Enhance this activity by counting as your child places "coins" in the slot and praise them for their effort as they work to slide them in.


Crawling requires coordination with both sides of the body as baby lifts their knee with the opposite arm simultaneously for forward movement. This is crossing the midline in action! Encouraging crawling continues to develop the integration of both sides of the body and brain.


Before baby can walk without support, they will begin cruising and holding onto objects for support. You may notice your child crossing their hands as they grab for support while cruising along - this is crossing the midline!


Whether your child is beginning to walk or starting to walk confidently and use their body for complex movement - walking is really where ‘crossing the midline’ starts to come together. This phase is the culmination of so much cognitive and physical development since birth and activating the midline can really start to take on a new